Here is the best advice I can give you about strategy in one pocket.
1)Whitey is the most important ball on the table. Never sell out whitey, and it will be hard for your opponent to gain any momentum and win.
2) Choose shots that favor your ball count. For example, if you have a tough shot that sells out more balls to your opponent than you can make on your run then choose a different shot.
3) Become more conservative with your shot selection when you are way ahead in ball count. Make the player that is behind take a chance. I have lost a lot of games trying aggressive shots to make my last ball and selling out in the process. Patience will get me an easily makable shot most games.
4) watch for your opponent's strengths, weaknesses, and tendencies. If he banks poorly, tempt him with a few bank shots and he will probably sellout. If he is a threat to run alot of balls downtable, then focus on moving balls uptable if you are behind or to break his rythem. Play tight players with alot of move shots. Play loose players tight.
I would focus my practice in two ways, runouts and bank shots.
When you are practicing, drop balls randomly then try to runout in the tougher pocket. When you miss watch where you sold out and remember that for the games. Remember, unless a shot is unmissable, whitey is always the most important priority.
Practice a ton of long and short rail banks with different english. Again, it is not good enough to pocket the shot. You must be able to control where whitey ends up. Honestly, the best thing that happened to my banking game was Freddy the Beard's DVD. It taught me so much about banking and my one pocket game improved exponentially.
Finally, find as many good one pocket players as possible and play them. You will learn how to move and choose shots by watching them. You will also learn what shots not to hit. I cannot tell you how many times I have shot what I thought was a good safe or move, walked away from the table smiling and proud of myself, then watched a better player either stick me worse or runout from a spot where I thought I was favored. Playing players only at your level will not build this sort of experience. It will take you a lot longer to get good at this game.
Sorry this was a little long winded:frown: