i use a small adjustable crescent wrench,regualar small wrenches are fine too(sockets use too much force).
i pretend to be a small girl and tighten my nuts until they are snug. then i grab my engine(still pretending to be a small girl) with 2 hands and try and move it back and forth,if it moves then i tighten one more turn of the nuts and try and move it again. when the engine doesnt move then i add another nut(double nutting) to all mounts and i turn the second nuts only 1 turn until snug(dont want to strip the threads). dont forget the muffler strap,that one you can tighten like a man,if you ever have a mount break,the strap might just hold the engine on the bike.