I feel too many people do this and hamper themselves. You can throw away an at bat just by being too patient. You should only take pitches that are out of the strike zone or pitches that you can't handle. You don't have to swing at every strike (Unless you have 2 strikes and are in protect mode). Some strikes are what I like to call pitchers strikes. Strikes that are in great locations that are meant to either look at or hit weakly. Learn to swing at the strikes that you can hammer.
Something I agree with in theory that another poster mentioned but not everything about it is learn who you're hitting with. That I completely agree with. If he is a speed guy use his speed to get on base. Don't try and hit the ball out of the ball park. What I disagree with is the power swing part. I use power swing with everyone. Depending on the count. Obviously more so with power hitters than with like he/she mentioned with 35 power guys. That doesn't mean you can't use power swing with weaker guys. If the count is in your favor, you're looking for a certain pitch, and you get that pitch don't be afraid to use the power swing. You are going to hit the ball with authority and if it finds a gap you can really do some damage. Not to say you can't do that with X but I find no matter who I use when I use [] on a pitch with good timing and I have the PCI in the right location I hit the ball much harder than I would with X. It all comes down to timing as well.
Glad to see others get involved with this and provide some more tips. I'm also glad to see people voicing the issues they are having.