As you can see, reselling at 12.4s with a buy price of 10s will only net you a 54c profit which is hardly worthwhile unless you are dealing in bulk trades. You will want to be making about +10% of your buy price per sale (which means ideally reselling at just over 30% over buy price).
I hope this helps some of you, and please and feel welcome to let me know if I have made any errors in my calculations.
As soon as part of any buy order is partially completed, immediately turn around and re-list the item for sale at the T1 or T2 price point (which ever is lower than the current Sell price). You are going to make most of your money through these rapid trades.
However, watch out for items with a lot of trader activity as it can sometimes pay off to only list 2-3 of that item at a time to avoid market saturation.
Cancel all buy orders once you are done with your trading session as you don’t want the market collapsing on you overnight. This is a really easy way to lose lots of gold.
Don’t make your buy orders too big. It works best to limit your buy orders to a maximum of ten units for any non-crafting materials, again this helps to prevent you holding too much stock in any item in the event of a market crash.
Choose maybe 5-10 different items that are providing a good margin and rapid turnover and focus on those exclusively. If a buy order is not fulfilled within 30 minutes then you will probably want to cancel that order and find something else.
Test each potential trade opportunity by first placing buy orders for 1-2 or that item and then seeing how long it takes to resell. Again, if you cant comfortable resell within 30 minutes then make a note. I would advise just re-listing at slightly above the BE value just to get your money back in these situations.