I would agree with everyone when they stress "form." Make sure you read up on books and articles and fact check for validity. Any time you strength train for a particular sport in a gym setting (with weights) you want to make sure that it is functional. Sometimes people forget that the word functional is relative, meaning that the meaning of the word is dependent on what you are planning to use it for. It would be wise for you to not only work on your larger muscle groups, but also your supporting muscle groups. Also, make sure you work your back, as much, if not more than you do the frontal muscles. You don't want to create any major muscular imbalances or discrepancies, like how many people have huge anterior delts and a flat posterior delts. Not only does this promote overcompensation that can lead to injury, but it also promotes bad posture. Everything ties in when it comes to body anatomy and function. As far as the type of exercises and styles of exercising, both MT and your bjj would benefit more from explosive training (but more for your MT) whereas bjj and grappling will benefit greatly from cardio and training that requires time under tension.
Don't worry about physique for now, any aesthetic gains will just happen as they come. Think of a cut/chiseled look as a desired byproduct of good strength and conditioning. Your body will naturally fill in over time. It's good that you are starting early so that it will establish a good base and the work you put in now will carry over time.
You can PM me if you are interested or feel like you could use my advice.
Also, don't forget about your diet.
