Icons?

[not-my-century.livejournal.com]

*hangs head in shame* I feel like such a noob for asking this (well, technically I am one, as I've had an LJ for only a few days, but I've lurked around various comms for months) but...

What's the etiquette for using others' icons? I've found several I like under the graphics: icons tag here, but was too chicken to post anything on the lists because a) they were all originally posted months to years ago and b) I've no idea how one goes about crediting the maker of one's icon.

If you guys could help me out with this, it would be much appreciated. I'd also love recs for finding more icons if you have any. ^-^