You pretty much got the biggest one but...
In general, you want to watch your minimap. If you haven't seen the enemy jungler in awhile, assume he's about to gank you. If you are toplane and you see the jungler bottom, take another look at the map in about a minute. You aren't likely to get ganked before then. If the enemy jungler ganks mid from topside, and leaves assume that he will be up to you in the next 15-20 seconds until you see another appearance.
Using those general rule of thumbs, play aggressive when you know you have a good window without the enemy jungler. If you don't know where they are or they were mid on your side assume that they are going to be ganking you soon. On my 2nd or 3rd back I'll generally grab an extra ward beyond my trinket. I'll usually wait to ward until I see the enemy jungler since he could be in those bushes waiting for me to facecheck as I ward. Once I see him, if he's far bottom, I'll wait 30 seconds to ward (this is assuming I'm top). If he's mid, I'll ward immediately and like I said, if I don't have vision I'll place a ward if I know I'm pretty safe (my laner is pretty far away) otherwise I'll play passive until I'm given an opportunity.
An extra tip, is that people will often place a pink in one of the solo river bushes near mid or behind their red buff to get some easy vision. (You are more likely to lose the pink in the river, but it's a lot more valuable for vision. Essentially it's a bit of a risk factor if they find it or not.)