Another leftie using arrow keys for movement. What else can a left-hander use? IJKL or even PL;' I guess would be an alternative, but still feels a bit cramped with the mouse too close-by.
I have Del and PgDn for lean in games that have it. 
End for use. 
Numpad . for reload. 
Numpad 0 for jump. 
Right ctrl for crouch. 
Right shift for sprint. 
Enter for melee. 
Numpad 1 for zoom or other weapon function not covered by 2nd mouse button. 
Other numpad keys for select weapon/ability.
Of course, that's still fewer keys in easy reach that with WASD, but it's usually enough. For games with more bindings, I end up using Ins, Home, PgUP, numpad Enter, #, [, ], etc. And that does suck, I guess.