In addition to the good suggestions already posted, I also suggest: 1. Exploring how your cryoprotection is done in addition to screening chemical conditions. For example, you may want to test longer equilibration in cryoprotectant, stepwise increase in cryoprotect., very fast swish through cryoprotect., etc. If possible, try to grow the crystals in a condition that can be directly flash frozen.
2. This isn't often brought up, but I've frequently seen sharper diffraction from smaller crystals due to better freezing/fewer crystal defects. Good luck! ho
