i use T3's exclusively and have not had any issues. but i do all the above, plug the mouth piece with a q tip, wipe off all the threads, including the MVP2 threads, q tip the connector, i don't let the take get below 1 ml, i usually top them off when i get 1/2 tank. don't fill them all the way to the top of the tube, leave a few millimeters between the top of tube and the juice. ensure that your atty is all the way screwed in, my daughters new one was only on one thread and was leaking all over.
finally i gently blow through the mouthpiece to clear anything, then vape away. it seems like a lot but i just refilled one while typing this.