I used to do this method that worked really really well. For example, if the price of SIF Isco is around 50k, I would buy around 10-15 of him at 50k (depends on how much I got to invest). I then relist him for around 55-60k, I just keep reposting him at different prices during the day until I find the price that will sell. I always try to find at least 3-5k profit.
If he doesnt sell at the price I want then I take my losses and move on to a different IF. Back before the price range, people had stupid amount of coins so this method worked really well since its taking advantage of people not giving a fuck about a 5-10k difference on a card. I started out at 300k and eventually worked my way up to 1mil, then 2 then 3. The more cheap Fifa 16 coins I had, the more expensive the cards I invest in although I do limit them to under 500k. I would aim for 10-30k profit on those more expensive cards.
At 1 point I had around 10-15mil just for these investments. I would have 10-15 cards of 1 particular 300-400k player and keep reposting them all day. A good return would be 2,3 being sold each time I relist them and then I go out and buy more of them. If the market is hot and I spend all day on the auction house, sometimes I would make a mil a day.
The amount of people buying cards above min is absurd, its like they don't use price range and just click search and buy w/e they see. I had a stupid amount of Fifa coins and sold them for some money back in February. This method isnt sniping and I'm not some savvy investor that knows who will rise or fall in prices. This took advantage of 1 thing and 1 thing alone, kids with alotta coins not giving a shit about the prices. I've took a couple of heavy hits from market crashes because of the amount of cards I would have in my trade pile. But the method makes far more money than the occasional losses so it all worked out in the end.