Here's a looong answer from me. I love my Birmingham save, so I have lots of opinions on the subject
If you still have money, use them on defense, and a bargain striker. Midfield also needs reinforcements, but that can be loaned (if there are still good loan prospects available).
- See if you can bring in
Leigh Griffiths from Wolves (on loan at Hibernian in 1st season, should cost about £500k. A bargain!). He'll get you lots of goals as adv. striker/poacher. If you need some more experience up front (I guess Zigic is injured a lot), bring in Marlon Harewood on loan for the season. He's at some chinese club, and will gel straight into your team as a target man.
- You have some decent Championship players in defense (Ridgewell, Davies, Pablo, Carr is a decent back four), but scout for young "up-and-coming" defenders for backup and future. Carr will only do for 1st season, and Caldwell is very inconsistent (I only used him when Pablo or Davies was injured or needed a rest). Spector can step in as CB and RB in emergencies, but it's not an ideal solution. You definitively need another LB and RB as backup for Ridgewell and Carr. Or check the avilability of someone like Nathaniel Clyne, Crystal Palace, as he can play both positions.
- As I prefer to play with wingers, I would look for an AMR (maybe looan a decent reserve from a PL club). Beausejour is an excellent AML, but even though Fahey is decent as a wide midfielder, he's no good as AMR.
Nathan Redmond is a future star, and will develop very fast if he gets first team football. He's a natural AMR and very versatile. So if you train him as a winger with 'new position: AML', he can step in at both wings when needed.
- Fahey, Mutch and Spector are ok in central midfield (
Mutch will become a good Premier League player if developed right). But they are ususally not able to dominate midfield. If you can afford it, look for a dominant midfielder with good passing and decision skills. If you can't afford it, look to PL reserve teams for loan prospects.
In my experience, to get promoted you need to be consistent with your tactics, and fairly cynical too...
Train your team into two or three formations/tactics until the players are fluent in them. This takes time. If you stick with using two different sets of tactics, it still takes a couple of months until the players are really comfortable with them.
Use controlling/attacking tactics ONLY when at home or when beeing huuuge favourites away. Defensive/counter tactics against the strongest teams (also at home), and almost always when away.
PS! For effective counter tactics, you need really fast attackers and/or wingers, and decent passers of the ball behind them.
Good luck!
PPS! If you get promoted, you might be in for a pleasant surprise. In my save, the club was taken over by some consortium a couple of months into 2nd season. As I got them promoted, I was allowed to keep my job (well, of course!), they gave me lots of extra transfer money (£35mill.), and renewed youth and training facilities. They're expanding the stadium atm (start of third season). As everything looks so bright at the moment, I'm just waiting for something catastrophic to happen, lol