This is a very powerful mantra of Lord Vasudeva using which Dhruva achieved the impossible.

va is the mantra for svadhishtana chakra
su is the root for the sun god surya the illuminator
da is the beeja for god as a father and is also the beeja for lord vishnu(dam)
ya is the mantra for anahata chakra. this mantra opens and connects both,while bestowing true knowledge of the self

Also it is an invocation to the supreme truth manifested as Vasudeva.


If you want more devotion to lord krishna you can add om kleem krishnaya govindaya gopijanavallabhaya swaaha to this


And the best vaishnava mantra according to my limited experience is
om raam raamaaya namaha