First mix your ketone with alcoholic methylamine, coll it and at 5 C more or less add the borohydride, slowly, let cool and add a bit more, cooling, don't let temp go higher than 15 C or so, an ice/salt bath works fine if you are not working with big amounts.
Don't add the borohydride to the methanol and then drop the imine, NaBH4 reacts immediatly with the methanol.