I am always asked about writing tips & suggestions. The best tip I can give is to join a writer's group!
Nearly every town has one. Many times it is in connection with a local college. If you have a Barnes & Noble or a Borders, quite likely they have a group that meets there at least once a month.
There are numerous groups online, too. If you go to Yahoo Groups, you'll find many! There's also websites such as Urbis.com. (See links.) At DeviantArt.com, there are dozens as well - I even co-manage one called The Writer's Meow. (See Links.)
Whatever group you choose, it will be a great exercise for you to share your work with others and get feedback. Some have assignments or contests. But they will all force you to stretch a little and develop as a writer.
So happy writing!