Ok, I would first of all, look at the best possible tactic to use. Eg. a 4-4-2, 4-3-3, 4-2-3-1. Then look and the best players in the squad. Charlie Adam from the top of my head is, alongside Luke Varney and possibly Michael Vaughan.
With that, I would try to see if they fit into the tactic. If not, work the tactic around your best players and start to mould them into playing their best positions. If they don't, then retrain the players into those positions, working on their weakest attributes in that position.
Next, I would work from the defence up. Build the strongest defence you can with a possible Stopper/Cover combination or even Ball-Playing/Limited combination. Then set one of your fullbacks, preferrably the slowest or who has the poorest crossing, to defend and the other automatic.
Have a deep defensive line, one of your defenders specifically man-mark a striker every game and the other to zonally mark. They must have good Anticipatio, Decisions, Marking, Tackling and Composure. Set a deep defensive line and counter.