The best way to generate extra income from the transfer market is by buying young players and improving them for one or two seasons. They will increase a lot in value. You can also use the transfer market to increase the strength of your squad.
It's important not to pay too much though, because there will be a chance that in two seasons there is less interest in this player and you won't get the same profit. As a new team it's not advisable to try to buy exceptionally good players. This will cost you a lot of money and because your training complex is not high enough they may not be exceptional any more when you try to sell them. You also won't need these players in a low level league and if the rest of your team is not equally strong this player alone won't let you win matches. It's better to gradually improve your team.
Old players (28-32) are cheap. You'll probably find it hard to sell your own old players, but it may be possible to find affordable old players that are still really strong. It can give your team a temporary boost, but all the money spent on them will be lost because you shouldn't count on being able to sell them again later.
If you are looking to promote to a higher league level, loaning some talented players from stronger teams can also be a cheap way to get a temporary boost. It may be a waste of money though if you fail to achieve promotion so consider this carefully.
