Nice gift! I think you'll like using them.
I'm guessing that you are talking about CTO gels. The amount of warmth will depend upon the gel. The best way to find out is to just experiment with them to see what the effect is.
A 1/8 CTO is good for taking the paleness out of skin.
A 1/4 CTO works nice on a hair/accent light.
A 1/2 CTO is as far as I have gone.
As far as pitfalls, my major one was when I was shooting print film. The lab would filter out my filtration. Not a good situation. If you shoot slides or digital, this isn't a problem.
Attached image shot with CTO gels. Sorry, I don't remember which ones.
Enjoy working with your new tools!
My toe hold on the web