coming from someone whose new year's resolution was to bumhunt (going slovenly btw), i can say that three things that have worked best for me are as follows:
1) starting sessions slowly. i do think that the VAST majority of the name of the game is table deselection as you say, so whenever i used to add myself to 20 wait lists, i would be ok for the first 10 mins of the session but once a million wait list screens started popping up, i would be too busy buying into tables, playing hands i was dealt, etc to deselect tables. if you just add yourself to just a few wait lists and check out some of the games that are short-handed and take an orbit to see the table feels, then you should be able to always have a good grasp of what tables are good and why (know why it's good is nice because then when the fish leaves or when the people on your left get more aggro, etc, then it won't take long for you to deselect it)
2) knowing what you're looking for. this was a problem for me when i was playing 200nl (which is a COMPLETELY reg-infested stake), and i had an ego. any table with people to my left who didn't 3b much OR any table where i had a fish SOMEWHERE at the table (even a not that huge of a fish to my left, with only like 50bb's lol) OR any table where there was a regfish close-ish to my right OR any table where i thought a certain reg was bad and i could exploit him.... needless to say, i didn't end up on that great of tables where the money was really flowing that great to me. now that i'm exclusively bumhunting, i'm only sitting somewhere to the left of massive (like 50+ vpip type) fish at 250bb tables. if that means i only have two tables up at a time, then so be it. i'll just pay extra close attention to exploiting those table dynamics, while trying to find good tables elsewhere.
3. having a good "feel" for tables. this is prolly gonna be tough for most micro players to have, but most of this is recognizing how wide of a range you can play profitably from how far from the button. the more 8/7's wtih 2% 3b's sitting to your left and the more 90/5's sitting to your right and the deeper you are on the people to your right, the more you can limp behind the fishes' inevitable limps, knowing you're never getting iso'ed and the more you can iso yourself without ever getting 3b and the more you can treat the HJ like the BU because everyone who has position on you are seat warmers who aren't gonna exploit that position, etc.
how "good" a table is can't always be figured out by hard and fast rules like the number of "fish" that are at the table (since that term is relative anyway). sometimes i have a 30/15 type three seats to my right at FR, and i have to look deeper into how big of pots i can win against this player with how big of hands; how much he's limping--how much he's limp/folding, limp/call and folding flops, limp/calling and calling way too light post-- i have to get a feel for how much the people to my left are letting me getting away with playing a lot of pots with this player, etc. this takes looking at a lot of the non-standard stats and it takes an orbit or two to really get a sense of how much of an advantage you REALLY have at the table.