Noob: should I level or go for better monsters?

I'm level 23 now. Running 5 A monsters currently. Should I be trying to level or get better monsters? In other words buy summons for more monsters or EPs to level. Don't really understand importance of level or if grinding missions is all. I'm not sure I understand the progression of this game.

The more you level, the more points you get to put into Energy, or BP. Once you have some REALLY powerfuly monsters and you want to battle, then you're going to need a LOT OF BP

Don't buy summons. You're better off buying EP and using those to buy monsters that are way better than the ones you have now.

Find a decentlow level a or a+ team with combos first, mine for instance is covert demons. Once you have 5 you'll get nice combo bonuses, and then you should level those to max. High level is only effective if you have combo bonuses.

By low level i mean low bp, like 15 or less, unless you get lucky