I've realized I'm quite clueless 3-handed (worse than HU and much worse than 4-handed) and this perhaps will help some.
Let's assume you join a table where two other players play (a couple of scenarios):
a) passive fish + straightforward TAG
b) passive fish + good LAG
c) aggressive spewy donk + straightforward TAG
d) aggressive spewy donk + good LAG
It's off hours and you think nobody else will join for a while (otherwise it's simple imo - get position on the bad player).
So a 6-handed table like this:
<font class="small">Code:</font><hr /><pre>
B C
A D
F E
</pre><hr />
Bad player sits in seat A; better player sits in seat D. Which seat do you choose? Is it different in scenarios a) to d)?