1st of all WELCOME.....
A single pin is good if you are shooting 18-24/24-30 yrds depending how you set it,but then again bow speed and arrows play into the mix also...If your not that good at figuring outyardage a 3 or 4 pin would be the way to go 10-20-30 or 10,20,30,40 or 20,30,40,50...these are just examples.A single pin adjustable is nice for 3-D shooting as long as you remember to move the pin between shots....
It takes some trial and error but you will find a sight that works for you,its just like finding the perfect rest......alot of trial and error...
Ive tried single pin,single pin adjustable,single pengelim pin(spl),3 pin,4 pin and just today I put a 5 pin 19mm Exreme sight on and love it.....Like I said...Trial and error....
Good luck