Hey,
so im new at buying coins on ebay but i have collected for many years. im hoping to start selling off alot of my coins soon but im still in the collecting stage. My question is how do i go about getting the best deal? and how do i know what coins are genuine and what are fake?

You don't, buy from dealers, and to get a good deal, don't bid over a certain amount, you won't win a lot of bids, but you will win some.

And expect to be cheated some, I have done maybe 40 to 50 deals on eBay and have been cheated 3 times, I understand that is fairly common.