Good question...
I personaly join where cross wind meets down wind. If i see conflicting traffic coming from the cross wind then I orbit in to the down wind. Mind you if there is a tower he/she should at least tell you of other traffic in the circuit. If it is FIS then I would expect/hope all pilots are making the relevant calls whilst in the circuit. This is one reason I like overhead joins.
FAA land also has a good method which is joining 45 degrees to down wind at the point where cross wind meets down wind. Usualy you get a good view of whats coming from cross wind at that angle and have time to either slow up or chuck a couple of turns in to buy some time.