I'm 13 and last year in baseball, I batted around .300, I had about 10 RBI, 10 steals, and 1 HR, and this is only in 13 games.

thats good. but when you get older, try to attend college camps so actual college coaches can evaluate your talent and your ability to take your game to the next level. try doing this your freshman year in high school. look for ads in newspapers, or search online for college camps you can attend.

not bad

That is not bad, especially if you are playing in a competitive league. But hitting .300 is not enough as a 13-year old; you must still attempt to get better if you have a dream of playing professionally.

At age 13 you are too young to do heavy-duty weight lifting. You still have growth plates in your bones (joints) and these can easily become compressed with weight lifting.

Your best bet now is doing calisthenics (push ups, crunches) and running. You will also help yourself if you play other sports as well as baseball. The physical conditioning of course will help, but you will also help your overall physical coordination by playing other sports.

Hand and wrist strength is very important in baseball, both for throwing and hitting. Get a rubber ball that is about the size of a tennis ball. slightly smaller than a baseball. Squeeze this ball often, working up to a few hundred times a day with each hand. This is a quiet activity, you can even do it in class while listening if you do not make a big deal of it. This helped Roberto Clemente get one of the best throwing arms ever seen. Good Luck!