The whole concept of FUT is to get you to buy packs. If you don't buy packs you're at a serious disadvantage. Very typical of the gaming industry at present to sell you a game, then to effectively sell you a subscription, whether that is via map packs, season passes, leaving things out of the game; forcing you to buy if you want the full experience.
A few people I work with worth spend about £30 a week on packs, once they get the top players they stick them on ebay and it pritty much pays for itself.
I don't play it myself so not too sure on how it works, but I suppose you sell on ebay, then make an in game transfer or put them on the transfer list for next to nothing.
If it still works the way it used to, basically you list the item on eBay, then allow the winning bidder to contact you with card information for someone rubbish, and you trade them whatever item you sold in return for the rubbish card.
EA have been trying to clamp down on it for years (alongside UT coin selling) but struggle due to little loopholes (the seller actually lists an online e-card as the item with a *FREE* million coin UT transaction). Amazed they still get away with it really.
Not sure if you are still interested, but here goes anyway seeing as FIFA 15 is just round the corner.
It takes a long time to build up a good squad, and you can get really good squads by just having patience. My advice is buy gold premier league players for 300 coins and make a reserve team full of them. The reserve team can be used for offline matches, saving contracts and regaining fitness for first team. Once a reserve team player has run out of contracts, discard the player and you will get a minimum of 300 coins, +4 coins for every raiting over 75 for every non shiny and +8 coins for every raiting over 75 for every shiny. This way, you can win offline and are not wasting money on contract cards and fitness cards. Then just buy a replacement 300 gold player.
Equally, buy gold prem playes for 300 coins and sell them for minimum 350 on the market, this works especially well at the start of ultimate team. Small gains, but all help.