It depends on what route you've decided for your sin.
Kobold clips - For crit
Yoyo Clips - For flee\dodge
Crit Rings - For crit
Those are the lower tier, more popular choices. I personally prefer using both a tele clip and osiris clip.
There are also quite a few more which are usefull, but maybe if you posted some more information about your sin I can be of more help.
