I've been having some problems with my starter.

when the engine is cold.. it starts 100% of the time, no problem.

But if the engine is warm, about half the time it gets cranky and doesn't like to start.. just sits there and goes 'click' when i push the starter.

I've heard some suggestions that maybe the starter might be overheating and a heat shield may do the trick.

Does anyone have any suggestions? Thanks in advance!

Let's start with the easy stuff; Check you battery cables and make sure they are nice and tight. Now check to see if the ground is nice and tight (had a simmilar problem on another vehicle..cranking down the batt cables solved it)
Now have a look and the cable from the batt and or relay that goes to the starter..is it beat up? Is it tight?

I've checked all the cables and everything looks fine. Any other ideas?

I don't think you should require a heat shield unless you are running headers.

If you checked all battery cables to see that they are clean, then you might have a problem with the starter relay or the starter itself, may need bearings and brushes.