If you have a hill, you have a great place to train. Do a lot of stretching out beforehand and some light plyometrics.
If it's a dirt hill, it's great because you can do this a few times a week. 1-2 times a week if it's asphalt. For below, the hills I've run on were always about 30-40 degrees from the horizontal.
Okay, we did this every Friday for NCAA track. We started at the bottom and went all out up to the top. Focus on your form and stride. Place a marker near the top to make it as long as a soccer field and make it your goal to go all out until you pass the line. That means you don't decelerate until you've passed it. Then you jog down to the bottom and when you reach it, you go again.
I did one day of this for each of the last two weeks. The first week I was not very confident about it and I did 5 before being done. The second week I made it my goal to do 8 and I made it to 8. During track we did 12 and were up to 16 without stopping and the distance was 50% more. You would of course not run further than you would have to on a soccer field and eventually, you should be able to do about 12 to 16. When you're at that level, you will notice a change when you play soccer
Just visualize making a breakaway run with defenders trying to pull you down, but you are just powering your way through like Kaka. Then when you jog back down, don't walk but treat it like a game situation where you jog lightly and are ready to receive the ball at any second. They're tough, but hill sprints do a really good job for explosiveness. They work wonders for your confidence if you can get yourself to the point where you are bent over breathing heavily, but instead you tough it out and jog to finish it. Cuz in a game, you can't bend over and breathe, or you'll get to sit on the bench.