This is just a stupid tip, but I’ve found it useful on many occasions.

Let’s say you’re overseeing some coworkers and assisting them with… whatever task.  They have a RAM preview up, and you see a blip in their mask or paint, whatever, and you want to put a marker on that spot.  BUT, you’re a busy MFer.  You don’t have time to site there and find the EXACT frame of the error, so why not just make a timeline marker while the ram preview is looping?  Here’s how:

Make sure you have no layers selected.  While the ram preview is looping, press the * key on your num pad, and After Effects will place a marker on the timeline at the exact frame you pushed the key on.  Bang, close enough right?  Now tell your coworker/intern to go find the blip that you know you saw around where that new marker is.

If you want a layer specific marker, do the exact same thing except have the layer you want to mark selected during the ram preview.

Hooray, my first quick tip!

Have fun marking the hell out of your comps!