-If you bought it with FSP then sell it for FSP not gold.
-Don`t sell it for too much more or else no one will buy it.
-Practice selling it for one gold more or 1 FSP more then when you are more experienced you can start selling for 40 gold more or 4 FSP more.
-Do not do this all the time ~ chances are there are going to be more cheaper prices and the same item.