I've experimented with different formations, I got promoted using 4-5-1, but the higher leagues seem to favour 3-5-2, or 4-4-2
I used the scouting reports to select the most likely win scenario against opponents, by doing a report for each of their most used formations (from the list available. It worked well until the last few games of the season when every bot team seemed to play a formation that was better suited to the one I'd chosen (i.e they didn't use their most common formation). Add that to inuries to key players and I just missed out on automatic promotion and even a place in the play offs, finishing 5th.
Defence appeared to be my weak area, so I've been improving my squad over the close season. May not be finished yet as I lose three decent loan players at midnight tonight, so I may go for a loan player or two.
Training complex finishes upgrading in about a minute (level 4). When I've established the cash, next it will by my stadium to a 4000 capacity, then youth centre will go to level 5.
I've been trying to upgrade my health centre along with training complex as the training complex supposedly increases the chance of injury and the health centre counters that, plus reduces fatigue.