Pick a weight for the movement that you can perform reasonably clean for the desired reps and rate of perceived exertion you're after based on the emphasis of the training phase you're in. If you're going to be using the movement for a long time, start on the light side and give yourself room to grow, so to speak. If you're going to wave the move for 3-4 weeks only, you can afford to get more aggressive.
Basically, pick a weight to do some for a few. And don't be a p*ssy. It's just lifting weights after all!