And then-- of course there are also people who express it through material means.

Like giving gifts and money.

I appreciate all of these, but for the last one--

if done excessively can be potentially insulting.

Friends are supposed to be equal-- if you give so much material goods, then somehow it seems like you're buying our friendship.

I personally prefer small but well-thought of gifts---

Not necessarily expensive, but they /know/ I'd love it.