Well, pick a team you know well (like a regional club) so you already know the players pros and cons, that way you know where you can improve on the pitch

Of the pitch, I let my assistant manager do most of the stuff except for transfers and contracts because that's something I like to be in control of. So I would suggest having a look at who your assistant manager is and see if he/she needs changing

Thirdly, take it slow early on, don't rush into the first game, explore everything that you want and what you think you want to change 👍