patience is the trick, I believe I read the average sale at sedo is like 230-260 days somewhere, I have sold domains the same day I bought them and others I have held for 2+ years or better before selling. List your domains at sedo, afternic and any other places you can find to list them for sale as more publicity is a good thing. Link to your domains for sale through forum signatures. In the end if you are sitting on something premium you will be found, but until you are found as much publicity you can bring to them will help. You can sell domains through forums for maximum dollar but the forum you are targeting has to relate to the domain you are selling and contain the end users, selling a "cooking" domain at a domainer forum like namepros will not bring max dollar, selling at a "cooking" forum could. List everywhere possible and send targeted visitors to your listings.
I can list a "cooking" domain all across the board and when they buy it will show that sedo made the sale, but truthfully yes sedo closed the deal but it was my efforts that produced the sale as I sen't hot leads directly to the parked & offer page. "Cooking" was just used as an example, substitute with the type of domain you have.