Another advise is to go with a 4-3-3 formation. This formation only requires 6 different types of players (ST, MC, DC, DL, DR, GK), which allows you to greatly reduce your wage budget as you will need only a few backup players. 4-5 STs, 4-5 MCs, 3-4 DCs and a DL a DR and a DL/R, and a goalie or two (I usually only have one goalie as in FM my GK is injured maybe 1 match a season on average and I can do with a youth-goalie there ;). As this can reduce your payroll with the salary of 5 players this will allow you to use that spare money to obtain better players/staff

Or just to make sure that your club doesn't go bankrupt.
Additionally, I have found that when attempting consecutive promotions you have to spend tons of time finding the optimal players for your squad, who are not too expensive, want to go to your club and fit your style of play etc etc. Especially if you start with a low-reputation club, it can be a paaiinn in the arse to find players who want to go to your shitty club and play at your shitty stadium
That reminds me that it is essential that you pick a club with a decent stadium when deciding which team to play with, as the amount of seats will determine a vast amount of your revenue in the first seasons.
Also, when your club starts to have a fair cash balance, you should start upgrading your facilities immediately, as it will improve your chances of obtaining the signature of a player as well as quicken the progress of your (young) players
and improve the quality of regens you will be receiving each year.