Congratulations, Neomyster! I hope you're happy with your V4 and V5.
I own four tamas, and two of those are the V4 and V5. You are able to care for both of them. You'll probably spend more time with the V4 because you have to earn it skill points so it could have a job. And since the V4 has weight (if you're concerned about weight), you'll find yourself spending time playing games to drop it's weight if you leave it alone. But spending more time with the V4 shouldn't be a problem, since the V5, in my perspective, is easier to care for. You could leave it alone for hours and it wouldn't die, so you really don't have to worry about the V5 all that much.
As far as tips and tricks, on the V4, you can determine whether you get a Mametchi, Kuchipatchi, or Violetchi by teacher and games. For example, if you select Mr. Turtlepedia as a teacher (you'll find out more about your V4 as you play with it; it's very simple to understand) and play Shape a lot, chances are you'll get a Mametchi. Mrs. Flower and Dance will help you get a Memetchi, and Mr. Canvas along with Flag will help you get a Kuchipatchi. There are also new characters you can get by playing the games, and it doesn't hurt to try different combinations.
Hope I helped, and good luck with your new tamas!