for me, I prefer to sock these compounds into your crystal. it will much more easy than co-crystallizaiton. But each protein should be different.
Normally when I star to co-crystallization with small compound, I will set up the complex with 1:1.2 molar ratio as first trial to see what should happen. As DMESO, you can't get rid of them. But you can find as much lower concentraiton as you can.
