Turn singles into double, take the extra base on the ball in the dirt, and every now and then swing for the fences if the situation allows for it.
Aggressive play is what makes the game fun to watch, when you come to the park you want to see players stealing, hustling, and diving whenever they get the chance, it is exhilarating. Players need to learn from an early age to put pressure on the defense and take advantage of the smallest mistakes, and if you have a reputation of playing hard and trying to take extra bases you will force teams into making mistakes they would not normally make because they will hurry themselves or take their eye off the ball.
The best way to be aggressive is to round first base hard and look for any opportunity to take second base. In your head you need to know that any bobble is a good reason to take second base, and if you see it, go. No hesitation, make mistakes going forward. A hard round will also cause the outfielder to get the ball in quickly and this opens up the door for an overthrow, under throw, or a mishandled ball, all of which give you a chance to get to the next base.
Taking the extra base on a ball in the dirt requires a player to be ready for this to happen and look forward to the opportunity as well. You have to have an aggressive mindset when it comes to the ball in the dirt. A base runner needs to read the ball in the dirt before it hits the dirt. If you see the ball is not going to make it to the catcher in the air, you can take off. In order to get thrown out the catcher has to scoop the ball and make a perfect throw which is not going to happen very often.
Steal signs come from the coach but if you are a good base runner who is aggressive you will probably get more chances.
Remember getting to home is the goal and any thing you do to get yourself one step closer only helps your team, and is a big blow to the other team.
Take advantage of mistakes and gain a reputation as an aggressive player in order to create more mistakes. Go out and play hard and play to win.