Sparge the solvents you're using with inert gas. Evacuate a hot schlenk tube and let cool to room temperature. Against a backflow of inert gas, add your material. Canula over your sparged solvent. Stopper the flask under argon flow, then seal. Stick in the freezer. Let crystals grow.
As for your question of increasing yield of one enantiomer, that doesn't have to do with recrystallization, but rather the reaction conditions themselves.