Things to consider that may make you a better goaltender:
1. Focus. Focus is a critical element to being a good goalie. It's often said that goalies who are having a great game see the puck as if it were a beach ball. Goalies who are struggling make it seem like a golf ball. And it's true. 'Seeing' the puck is just as important as how you stop it, because if you don't 'see' it, you can't stop it. Where I play we have a 5 minute warm-up and even though I'm mostly a butterfly goalie, I won't go down once during warmups. Why? Because warm-ups isn't about stopping the puck. It's about getting mentally and physically ready to play. Once I'm stretched out I work on focusing on the puck and slowing it down mentally, that way when the game starts, I'm mentally prepared. Be sure to watch the puck all the way into your equipment.
2. Reading the play. If you have a background in hockey this will help tremendously. You need to be able to understand what players want to do with the puck and where your defensemen are playing. Is someone standing on the backdoor waiting to receive a pass? If you know he's there you can adjust your angle to account for him. On a 2 on 1 is your defender taking the puck carrier or the trailer (he should be taking the trailer and giving you the shooter). If a player is behind the goal line is he planning to go to the net with the puck or look for someone to pass to in the slot / point. A lot of this comes with experience but the better you can 'read' the play the more often you will be in position to make the save.
3. Actually stopping the puck. Yes, this is the 3rd most important element. If you excel at 1 and 2, this will be the easiest part. Two big mistakes I see new goalies make a lot. Holding the goalie stick, you need to have your index finger run down the paddle. This gives you control of your stick and is critical. Second, when you go down, be sure to 'stay tall'. Many goalies will go down and they'll be almost sitting on their heels or let their upper body slouch way down. Keep your upper body as upright as possible when you're in the butterfly. This will give you the necessary mobility with your gloves that you need and you can push from side to side much quicker. A previous response tackled angles pretty well so I'm not going to go into them. You want to be at the top of your crease at all times if the puck isn't any closer than the hashmarks, square to the puck of course. I disagree with playing the player on breakaways. If you aren't square to the puck the shooter will know this and take advantage of your angle and very likely beat you short or far side. Defensemen play the player, goalies must square to the puck... you're not trying to stop the player, you're stopping the puck.
4. Other things... I know it's a matter of comfort and most goalies are different but I prefer sharp skates. Some goalies like them dulled so they can slide around more but sharp skates allow you to do that while giving you the ability to push around the crease when you're down. If you're having problems getting beat glove side at all try moving your glove a few inches forward, more in front of you then to the side of you, this cuts down the angle even more. Kipprusoff in Calgary plays this way with his glove. Rebound control is just something you learn as you play, being able to give with your gloves and leg pads will help dampen the contact and keep the puck closer to you.
Good luck with the season!