Use whole object measurements
Make sure all the dimensions, object sizes, positioning coordinates, etc. are whole numbers. Every single measurement. Avoid any free-hand drawing. Instead, choose an object tool (ellipse, rectangle, etc.) and click on the screen. Enter your object dimensions manually. And once again – no commas!
- 64 not 64,12;
- 128 not 128,91.
All numbers should be even
Try to keep your object height and width measurements in even numbers (2, 4, 8, 12, etc..). Illustrations are meant to be resized, so imagine you are creating them on a 64×64 grid and make one object 15px x 21px. When you’ll resize your illustration to 32×32 (half), that object will become 7,5px x 10,5px, which will result in a blurry illustration.
Remember: by using the 64 grid system.
Use the transform box
The transform box is your main tool when creating illustrations. It should be always opened, and you should keep an eye on it all the time. (You can open the transform box by checking Window > Transform, if you haven’t done it already.)
Make sure there are no fractions in this box. W and H stand for width and height of your object. There’s no need to mention that all of these four numbers should be even. Check the transform box after creating every object to see if everything on the grid is where it should be. Often when you create a new circle it isn’t placed on the grid. (Circles are most likely to to go off the grid.) So if you see any fractions in the transform box, fix them by typing the nearest whole value. (You can as well use arrow keys when the input is active to increase or decrease values.)
And don’t forget about using correct object measurements. Once again: the main pixel perfect design principle – do not use any commas! Never.