Gridding - Paint Shop Pro (Photoshop)

There's a lot of confusion about grids. 

I use them for placing 'tubes' or other items that reqire precise positioning.  Otherwise, I 'eyeball' it.

Here's the simplest way I differentiate when I have to work with them.

If your piece is an off size, try resizing it up or down to the nearest number divisible by '5' and work up from there.   For example, you have something that's 317 X 404 pixels.  Cut the work out and resize to 315 X 400 pixels and you can use a 5 X 5 grid which gives you more control.  Then paste back in using the 'PASTE INTO SELECTION' option so that the resizing won't affect it.

I set my default grid to 25 X 25 for my tube work and adjust it from there other things.

Most of us think in grid terms of 1-100 and there's nothing wrong with that.  What causes problems is that computer monitors and resolutions do not use this system.  

They began with binary numbers and went on to 8 X 8 pixel points or whatever they were called back then.  By the time GUI's (windows) came into existance, 16 X 16 or 32 X 32 were the standards.  To make your work more 'Resolution Compatable' begin with sizes that are multiples of 16 or 32.  Two common sizes right now are 640 Pain X 480 and 1024 X 768.  As you can tell they don't fit into grids based on 10, but very well into grids based on 16.  

Your completed work - if used for a background will fit better and center more neatly based on those numbers.

Hopefully this is easy to follow.