Surround yourself with good grapplers. You're a product of the people you surround yourself with. If you surround yourself with people who are good at Jiu-Jitsu and want to get better, you will find getting better a lot easier than if you don't.

Show up. This shouldn't need to be said, but I need to say it if you train consistently, you will get better faster than someone who doesn't. Oh, and reading The Grappler's Diary every morning while sipping your coffee does not count as not count as training :(

Don't self-sabotage. Getting better at Jiu-Jitsu is already a pretty hard thing to do. It's hard to maximize your training time, push yourself, and put yourself in a place where you can grow. Don't make it harder by shooting yourself in the foot before you even really make a push at getting better. Do the best you can at the things you can control.

Tap early. Tapping late is a form of self-sabotage, but it deserves its own point entirely. The more you tap in the practice room (within reason), the more you learn. More specifically, the more you put yourself in positions where you make mistakes, the more opportunities you will have to learn from them.

Train with partners of varying levels of experience. Another really important and fairly easy thing to do. People will tell you to do the hardest rounds you can every day - and that's partially true. Do hard rounds, but also do rounds with less experienced partners.