Inkscape

DRAW STRAIGHT LINE
shift+F6
hold ctrl, click, then Enter to end

CROP
select rectangle tool
stretch rectangle over area to crop
then select all layers (Ctrl+A)
Object > clip > set

CROP a shape from a background
position the shape over the background layer (if shape is combination of several shapes, combine the filled-bucket images (of original) first using Ctrl+K)
select both shape and background
Object > Clip > Set

Change background to transparent
Path > trace bitmap
Multiple scans > Color + stack scans + remove background > OK
Drag image to different location... the background will have  been removed.

How to warp text (bend text evenly)
1. Select text
2. change object to path (Shift+Ctrl+C)
3. See Path Effects (Shft+Ctrl+7), then click "+" to add path effect
4. Select "Bend" > Add > Bend path > click "Edit on-canvas" >  Drag the green line until achieve desired shape.
(Note: More changes can be achieved if select "Envelop Deformation" instead of "Bend")

How to warp text (Method 1)
1. Select text
2. change object to path (Shift+Ctrl+C)
3. Draw shape (Shift+F6)
4. Select TEXT, (then hold Shift) then SHAPE, then Extension > Modify Path > Perspective
(note: u may need to adjust the text 90 or 180 or 270 degrees, then perform step 4, to get the desired orientation)

How to warp text (Method 2 - recommended)
1. Draw envelop shape (Shift+F6)
2. Text: Write all-caps > Object to Path (Shift+Ctrl+C)
3. select Text THEN select shape > Align & Distribute (Shift+Ctrl+A) > align so that 4 corners of text are close as possible to fill all corners of shape
4. Select Text (now it's called a Path) > Path Effect (Shift+Ctrl+7) > Envelope Deformation > DISABLE "enable left & right paths" (bcos u've adjusted the width manually) > ENABLE top & bottom paths
5. click "Edit on-canvas" for "Top bend path". Drag text's corner nodes to desired location. Then drag text's green line to desired effect.
6. click "Edit on-canvas" for "Bottom bend path". Drag text's corner nodes to desired location. Then drag text's green line to desired effect.

Edit paths using nodes (F2)
- drag an edge to curve it equally on both sides
- doubleclick to intro a node to adjust curvature of 1 side
- to make 1 side become a straight line, delete the node handle (on that relevant side) (how to delete: just drag the handle to the node and it will disappear by itself)
- to delete a node, click on an existing node and hit delete

How to font:
1. google a theme e.g. "western fonts"
2. pick a free font from dafont.com
3. to pick a complement, google "complementary western fonts"

How to draw a circle outline
1. Fill & Stroke (Ctrl+Shift+F)
2. "Fill" tab: select "no paint"
3. "Stroke" tab: select "flat colour"
4. "Stroke style" tab: select width (1mm), cap (square).
5. Select "create circles, ellipse, arcs" (F5). Drag and draw circle.

How to draw a straight line (similar method to "how to draw a circle outline)
1. Fill & Stroke (Ctrl+Shift+F)
2. "Fill" tab: select "no paint"
3. "Stroke" tab: select "flat colour"
4. "Stroke style" tab: select width (1mm), cap (square).
5. Select "draw bezier curve and straight lines" (Shift+F6). Drag and draw line.

How to do outline of text
1. Type text (F8) e.g. ABC
2. Paint bucket (Shift+F7) > Options: Threshold(15), Grow/shrink by 15px > select RED > click once on each text character. Each character will overfilled with RED which exceeds original border by 15px. Move each RED fill to the back (End button)
3. Paint bucket (Shift+F7) > Options: Threshold(15), Grow/shrink by 0px > select GREEN > click once on each text character. Each character will fill with GREEN exactly, no overfilling occurs.
4. Move the original text out of the way. Remaining are green characters on larger red characters.
5. For a given character, select the green fill and red fill (use Shift). Then path difference it (Ctrl -). You will obtain just the red outline. Repeat for remaining characters.

How to do make text glow
1. Duplicate your text
2. Move this duplicate text beneath the original text
3. Under "Fill and Stroke" menu (Shift+Ctrl+F) > "Fill" tab > "Wheel" tab > increase Blur to get desired glow. If desired, change colour or opacity of glow.
ALTERNATIVE: sometimes using GIMP's dodge function gives better results.

How to give your vectors a nice thick outline
1. Ensure your vector in question already has its desired shape and colour.
2. Select that vector, then duplicate it (Ctrl+D), and turn it black.
3. Black layer: Lower it by 1 step (Page Down), then give it a thick stroke (Fill and Stroke (Shift+Ctrl+F) > "Stroke paint" tab > click "Flat color" to turn it on >  "Stroke Style" tab > Width(25px) AND Join(rounded) AND Cap(rounded).
Now to make the outline a darker shade of the fill's colour:
4. (With layer of black outline still selected): Stroke to Path (Ctrl+Alt+C) > Break apart (Shift+Ctrl+K) > Union (Ctrl+plus)
5. Select Dropper (F7) > click on color of the vector in question
6. Fill tab > HSL tab > drag the "L" (i.e. lightness) towards black to darken the outline but still retain the shade as per the vector's fill colour.
Source https://www.youtube.com/watch?v=s41_-qsmA7s


How to give your vector a reflective sheen / highlights
1. Select vector and duplicate it (Ctrl+D)
2. Turn it white, then turn opacity down to see thru it (this is your highlight layer)
3. Shrink the highlight layer with inset (Ctrl+9) a few times.
Source https://www.youtube.com/watch?v=s41_-qsmA7s


How to shade or highlight with vectors (USE THIS FOR DESIGNS WHICH WILL BE PRINTED)
1. Bezier curve (Shift+F6) > draw rough shape of 1 contiguous shadow/highlight for intended area. Then modify nodes (F2) so that shadow's shape looks better.
2. Remove stroke (Shift+Ctrl+F > Stroke Paint tab > X) , let Fill be same colour as vector's fill (use dropper), then darken the fill (Fill tab > HSL > lower the "L" (lightness). [lighten the fill if creating highlight]
3. Move the shadow layer to appropriate level (usd Page Down)
4. Increase blur to diffuse the edges of the shadow (NOT RECOMMENDED if your design is meant for printing)
5. Trim any excess edges of the shadow layer (Duplicate the vector (Ctrl+D), then select both the duplicated vector (select it 1st) and shadow vector (select it last), then Object > Clip > Set).
Note: If 1 shadow overlaps 2 vectors, duplicate the relevant vector, then select the shadow and vector, and clip the shadow accordingly.

How to draw pixel art
1. Document properties (Shift+Ctrl+D)
> "Grids" tab > Creation (Rectangular grid) > NEW
> SpacingX (25) > SpacingY (25) > Major gridline every (1)
> Show dots instead of lines (tick)
> close window
2. Enable snapping
3. Fill and Stroke (Shift+Ctrl+F) > turn off stroke; turn on fill
4. Draw picture using a square (F4) into each grid as desired
5. To do highlights or shadows, pick a range of squares (use Shift+clicks), then adjust "L" slider in HSL tab in Fill and Stroke menu
Source https://www.youtube.com/watch?v=Se7WVuyIEnU

How to drop shadow for text
https://www.youtube.com/watch?v=70kPYd-tkDA

How to crop a specific shape around an image
http://goinkscape.com/how-to-crop-an-image-in-inkscape/

How to insert a (e.g. white) border around an object which is already has a transparent background (method does not involve time-consuming tracing)
1. Image should have a solid object with transparent background. You can achieve it by using this https://www.remove.bg/
2. Path > Trace bitmap (Shift+Alt+B) > select image > Update > set Threshold to 0.99 only (dont set to 0.999....) > Update > OK
3. Edit paths by node (F2) > delete whichever nodes which shouldn't be there (usually just delete nodes within the black shape). The black shape will eventually be converted from a bitmap image to a vector.
4. Fill and Stroke window (Shift+Ctrl+F) > "Fill" tab: (No paint) > "Stroke paint" tab: (Flat color, WHITE) > "Stroke style" tab: (width: 22px)
5. "Export PNG Image" window (Shift+Ctrl+E) > Export area (Page) > Export as (decide path) > EXPORT

How to make vector A overlap vector B (and not see the overlapped part of vector B within vector A)

1. Starting positions: vector A overlaps and is ABOVE vector B (at this point in time, can see both vectors A and B fully, with a portion or all of vector B seen within vector A)

2. Select vector A and duplicate (Ctrl+D)

3. Optional Step: To increase gap between portions of vector A and vector B which overlap:

• With the duplicated layer selected, increase the border width (e.g. set stroke width to 50px).
• Path > Stroke to Path

4. With the duplicated layer selected: 

• Path > BreakApart 
• Path > Union 

5. Shift+click on vector B (to select it). So now both the duplicated layer AND vector B are selected.

6. With both duplicated layer AND vector B selected: 

• Path> Difference

7. Now, u will see vector A overlap vector B (without seeing any part  of vector B within vector A)

Source: https://www.youtube.com/watch?v=OT97oRXZiVY (5.55-6.24)

WHY BUD (breakapart - union - difference): https://www.youtube.com/watch?v=JEPd-gCW5m8 (very good explanation)

Things to understand

https://www.youtube.com/watch?v=ZT3mp5qi0hM

"Object vs Path"

When to use "Path > Object to Path"

When to use "Path > Stroke to Path"

When to use "Object > Clip > Set"

Troubleshooting

Why doesn't "Path>Difference" work? I already have made my 2 vectors (A and B) overlap.

Path difference works only when vector A and vector B are individual (i.e. not grouped) vectors. 

If vector A was grouped together from smaller vectors A1 and A2, then need to ungroup A into A1 and A2 first. Select A, then ungroup (hit Shift+Ctrl+G) several times until see a message "no groups to ungroup in the selection". Then select A1 and A2, and union them (Path > Union) to become 1 unionized individual vector A. Finally, overlap A and B, then "Path > Difference".

For best results: 1. Start with a bitmap image (.png) of desired shape & size. 2. Trace bitmap (to get a vector). 3. Select that vector and hit Shift+Ctrl+G multiple times to ungroup and get rid of multiple layers of the same shape. Select only 1 layer (we call this Vector A). 4. Repeat steps 1-3 on a different bitmap image to get Vector B. 5. Overlap Vector A and Vector B. 6. Path > Difference.

Note:

Path>Difference - vectors must be individual, or unionized (never grouped).

Object > Set clip - vectors can be grouped