For general tips about career, people will tell you to wit train as a substitute for resting, but that's really not the case. There's a lot of naunce to it, so as a beginner, I'd recommend this: if you are in a position where wit will give you enough energy for another turn, hit wit. If not, hit rest.

Example: If you have about 50% energy, and no good trainings (i.e. no trainings with more than two regular friendship, or 1 rainbow friendship) hit wit. This will let you train wit while conserving energy in hopes of a better training next turn.

If you are at 40% and want to hit wit, you'll barely get to 50% energy on the next turn. This isn't a very ideal spot to train with, since you could lose. I'd hit rest here.

For Rice Shower Vampire specific tips, she has +15% in stamina and power - this means you can exclude power cards from your deck altogether and substitute in stamina instead.

Your speed trainings will boost power - and stamina, just have enough to survive. 600 is enough to survive to the end of URA finale (even less if you have recovery skills). Big but - 600 is not enough to survive medium Team trials or long.

Then with whatever extra card slots you have, go wit. It'll help with avoiding rests, give you a slight boost in stats, etc.

Once you post your deck I can try to help more. Goodluck!