The free transfers are very hard to get.
But If you can lose some time, you will see that some players are selling for prices way bellow there market value, try to buy those ones.
This is because you can sell a player for the minimum value 70%Market value or maximum 10%MV. Here you have an income of 20%.

Last season i bought one player, i sold him next day with an income of 490K, just because of that, i bought for the minimum and sold for the maximum.