Hey...had the same problem.
What you can do is a couple of things:
First, try to schedule a few friendlies against high profile clubs (look at the predicted revenue to get an idea)
More often than not, if you offer clubs like Man U or even Juventus etc about a quarter to a third of the predicted revenue they will play you.
Great income at the start (cancel a few of the away games that your stupid assistant scheduled to make room)
Next, here's a few key signings that helped me a lot:
Ian Harte (DL,old but quality)
Soley (DM/CM, not too old, will most likely sign)
Stephen Appiah (must sign; bets free transfer by far, not only young but good, he starts out ill from a virus; good news is, nobody is bidding on him because of that, bad news is it takes a bit of precision to make an offer the second he gets a bit better, otherwise he the trade will get canceled cos he failed his medical)
Zamora (plays all defensive rolls but best as right back)
Those you will more than likely get.
Also available are:
Edgar Davids
Fedorov
but those will be heavily bid on by many other teams so chances are slim they will sign with you.
Als a few relatively good cheap ones are Guus Joppen (DC, young, in Holland squad on my save now) and Adam Larsen (NOR/GHA goalie, very young, as good as Angkergen for around 400k if you're lucky; on my save he's valued at 3M now and he's fantastic)
Try to sell a few of yur designated subs to make cash for those, they're worth it.
Also, check out Adailton from sme Brazilian club, he's turning out great and you might get him cheap early on.
Another alsways mentioned is Vaclav Kadlec, you might even get him for free for your youth team in the January window.
As for Leeds itself, Delph is great, off course, but my biggest surprise was Howsen playing as a right winger, he was tearing up League 1 on the wing and is now (End of second season, 1st place in Chanpionship) valued at close to 5M in my save.
Well, I went a bit off topic, sorry....but Richardson is good enough if he stays healthy.
Good luck in your game, update some progress here.
---------- Post added at 11:50 PM ---------- Previous post was at 11:49 AM ----------
Also, something I found quite helpful for unearthing worthwhile signings is to scout the transfer rumors pages.
Check the leagues of your own level and a few steps above (World>Country of Choice>League of Choice> Transfer Rumors)
Many a time I found "Club X is looking to sign Player Y on a free transfer".
It usually gives you a good indication of the level a player can play in, and it's a lot faster than manually looking through the player search with filters.