If you could send us 50ml of buffer for each variable you want to try, that would speed things up on our end. For instance, if you intend to send your proteins in low salt, or in high salt, or in glycerol or detergent, or whatever (because that's where they are happiest), we would adsorb them to mica in that same solution, and then we would wash the mica in that solution, then we would wash the mica some more our standard salt solution (again, 70mM KCl, 30mM HEPES pH7.2, 5mM MgCl2, 3mM EGTA).
This last step we have to do carefully, to wash away any organics just before freezing (i.e., any glycerol, sugar, detergents, etc.), since they won't "deep-etch" without leaving an intolerable "scum".
Remember: send your samples FedEx PRIORITY to the address below, in a Styrofoam box with crushed ice. (It's best to pack the ice in a Ziploc bag and seal the Styrofoam box with tape so that it won't leak any water during shipment.) (FedEx STANDARD overnight shipments come too late in the day for us to have time to prepare them.) On the other hand, if your protein is frozen already, you would of course want to pack the box with dry ice. But please don't even think about packing your proteins with those "picnic ice" packs or other sorts of ethylene glycol packs. They tend to freeze samples during shipment, without any of us ever knowing it.