Training for grappling?
Get lots of grappling partners. It's too easy to figure out a person's game and come away thinking you've transformed your game when you start to constantly get your sole partner to tap. The truth being that figured out your partner's ground game and when he figures out yours, you're going to start looking like shit. Multiple grappling partners (different sizes and styles) will make you focus on what works, and will help you keep your mind in a place where it will adjust on the fly. Sharktank exercises/drill where you have 1 guy stay in while the others rotate in round after round will prove this over and over again, especially when you start getting tired.
If you're grappling, make sure everyone knows to give each other the opportunity to tap and has enough mutual respect to allow that. The worst thing for training in a grappling situation is to have some jackoff spaz out on you and A) Injure you or B) Injure themselves because they go gung-ho on a takedown or submission hold.
Find a good coach. Not just a credentialled guy, but somebody with experience. Thankfully, most folks that you find that are credentialed (from creditable sources) are usually very experienced, especially considering that most Black Belts in Judo or Jiu-Jitsu have usually spent anywhere from 7 to 10 years getting there. In which cases, many brown belts or purple belts will do a lot of good for you if you don't have a black belt available.
Finally, have fun and don't be scared to experiment. As rudimentary and mechanical as grappling is, sometimes the unorthodox and showy tactics will work with suprising results. Sure, you may not always land that flying armbar, but it's always good to know that you can do it.