These tips are taken from the 'Fast Bowlers Bible', well worth a read as it does contain some really good tips and how to not only bowl accurately but also add some extra speed to your bowling.
• Imagine you are bowling in a railway track. This will help you run-up straight, keep your weight moving in a straight line in your action and follow-through straight. If it doesn’t go at the batsman, then change it!
• Your non-bowling arm is far more important than your bowling arm. Use it properly by driving it out and down so it passes your side. When you do this properly, it will accelerate your bowling shoulder and help increase speed
• Keep your elbows and arms pumping in as you run up and load up into your action. Nothing throws your momentum and straight lines off like unnecessary side-to-side movements. Keeping your action ‘tight’ helps you to control the release of the ball
• Make sure you fully rotate your shoulders on completion of action. If you have a name on your back imagine you are going to show it to the batsman when you finish. This will help you think about how much of a shoulder turn you’re aiming for
The rest of the tips can be found
here as well as more information about the book.
The best tip I know in order to bowl accurately is too ensure your non bowling arm (at the elbow) is brought into your hip - this helps to keep everything straight.