The best way to really go about becoming a better swimmer is to join a local masters swim program. This will give you access to a pool and a coach. Prices vary by program. Many offer monthly or quarterly memberships and most offer you a few free trial swims.

You can find them here,
http://www.usms.org/placswim/mapsear...10570&units=mi

You will get actual coaching on technique and how to improve quickly. I have seen people come into our program who could not swim one length of the pool. In just months, they were able to easily finish a 1500-2000 yard workout in an hour.

If you cannot make a masters program work, then I will also recommend the total immersion DVDs. They can help give you a really solid swim base.

Swimming is a sport that will really benefit from the more times you practice. 3-4 days a week will really help significantly more than 1-2 days a week. Might be overkill for a sprint triathlon, but most people underestimate the swim and can experience serious issues in the water.

Focus on technique. Poor technique will hold you back more than poor fitness.