One of the best tips I was given at a conference in 2005 that John Reese spoke at was "split test" your sales copy.

That is have 2 sales pages split tested and change just one thing at a time on one of the two pages for eg the heading, the bonuses, the price etc and keep the other one unchanged.

Track your results and see which one sells more or gets more optins (depending on what ever your conversion goal for that page is) . The "winner" becomes your new 'control' sales page, and you make one change to the other page and test that.

This way you are continually improving your sales copy by proper testing and should be then improving your conversions.

This a great copywriting book below you can get at Amazon.

"The AdWeek CopyWriting Handbook" by Joseph Sugarman.

Anthony