There are many excellent books out there on selling strategies. Some in which I found were very usefull in selling. I found that that all books from the following authors have very good selling strategies and techniques. There are many more, but I found those authors are excellent .
-dale carnegie
-zig ziglar
-tom hopkins
-brian tracy
-richard bandler
-carleton sheets
-roger dawson (excellent on negotiating techniques)
Do a search on amazon on these authors.