I don't have any "tricks" wrt remembering which is where (110/70) and maths works for me, but I can suggest when you have a choice (and remember the 5deg of flex is heading dependant, which is why atc never give a particular sector - they don't work out your drift) the preference would be sector 2 is best, followed by a sector 1 and the sector 3 is last choice.
To understand why, look at which of the entries (when you have a choice) will have you conducting the entry closest to it's design.
Eg. If you have a 1/3 choice, the sec 3 entry will have your outbound leg a lot closer to the inbound leg. You will overshoot the turn and have to reintercept inbound. While the sec 1 will be further away on the reciprocal to the inbound, the intercept turning inbound will be easier.
