Sorry for not posting my approach to table selection earlier, I didn't have enough energy...
I don't do anything complicated, don't use 3rd party software (which might sound too expensive to liferoll nits, though I suppose it pays for itself very quickly already at PLO10). I just sort tables by the number of seated players (ascending) > waitlist length (asc.) > players per flop (desc.), never join a non-empty waitlist because they're usually filled by regs, which means that when someone quits the table, it will become too reg-infested as the quitter will usually be a busted recreational.
I've made it a habit to never close a table until I give every opponent a colour code (of the poker client itself), at least a provisional one (as few as 5 hands can distinguish a nit from a maniac) that can be refined later. It helps a lot in table selection because the HUD sometimes (on iPoker, always) fails to load until I play a hand at the table, which means that it doesn't help to decide whether to join a waitlist.
I join not all the waitlists in town, but only to as many tables as I want to load additionally (moreover, I try to observe them when I'm not involved in a hand, so that I'm armed by a bit of reads even before sitting in). Otherwise it becomes a pain when many invitations pop up at once and I have little time to decide which to accept, which to decline and which of the existing tables to close to give place to better ones. I first close bad tables (but as soon as they're spoilt, with little hesitation) and only then reselect an equal number of new ones.
Of course I prefer to hop onto non-full tables; apart from the obvious preference for having recreationals (followed by LAGs) as close to my right as possible and nits on the left, my approach includes joining tables with <=4 players (and not quitting most 4-player tables with 1 rec) so that the seat on my right is vacant (if a reg occupies it, I can just quit and reselect, but if a rec happens to sit there, it will be fantastic).
On networks with no waiting lists (Ongame, MPN), I certainly observe full tables I want to join and ninja-click at a seat as soon as it opens. SSPLO regs can't afford seating scripts anyway, so the competition for seats is quite level and honest.
All right, I've gone a bit offtopic... I find that the most effective method of beating regs 'at the table' is to go through hands vs them in the database and try to spot their leaks, first those of active regs with the most hands, as I face them more often and hence they affect my winrate more dramatically. Alas I'm not that proficient at taking notes while at the table, and it takes focus away; it's better to give hands a special mark 'Noteworthy' and then review them and write notes away from the tables.