Hi

I use the 'y' and 'x' keys for one frame at a time. Look ma, no mouse.

'i' and 'o' are also great for cutting. ('a' and 's' do the same but are too close to 'x' and 'y' for me)

'i' for start from here, in ( it makes a cut and deletes everything that was before )

'o' for end here, out ( it makes a cut and deletes everything that comes after )