I figured you would have had a decent reply by now you should try posting in the Fitness section too.
http://hfboards.mandatory.com/forums/fitness-and-training.253/
Since you have a shooting pad and a net shoot pucks for 20 minutes/day wrist shots, snap shots, some backhands, and slapshots if your stick will hold up or breaking it doesnt matter. Work on placement consistently being able to shoot top and lower right/left. Work on your release stick handle the puck 2-3 times and quickly get your wrist shot off. Work on putting your body weight into your slapshot.
Once you are comfortable shooting with the puck in a good position change your shooting angle, things like look top right and then place it top left, get used to shooting with the puck in uncomfortable spots such as a little too close to your feet, a little too far away, right in front of you, because you don't always have the opportunity to place the puck you are about to shoot. You can practice saucer passing from your pad into your net move the pad 15 feet from the net and try to get the puck to land inside of the net.
Working on your leg strength and cardio would probably be the most important thing you can do to improving your game. I have no idea where you are at physically so you might have to build up to some of these and you should do a light warm before starting. Something like a light 15 minute jog, skipping, or something like that to get your blood flowing and to get loosened up.
Wind sprints are extremely demanding you exert tons of energy and have to recover quickly like in a grueling shift. You would be able to do these at a track or open field near you, or even between hydro poles. Find a distance that works for you something like 50-100m, jog or walk a distance and then do it again, aim for something like 500m sprinted over 15 minutes.
Other things you should be doing are squats, jump squats, deadlifts, calf raises, I would go for higher numbered sets like 10-12.
Balance and core strength are also important.
This will also give you some ideas
Explosive Power Progression Charts