Hopefully you've heard of the book "TOTAL IMMERSION" by now. If not, you MUST read this book and do the basics drills if you want to improve at all. It won't make you swim like a pro, but it fixes the most common beginner errors of having incorrect body position (feet below head), which will severely limit your ability to swim long or fast. If you're in good aerobic shape, but can barely survive 8 pool lengths, you really, really must read this book.