Does anyone have a good guide on this? I feel like the starts of my save are always messy and I forget many things that later on hurt me. Been trying to find a proper guide but I haven't been able to.
There's a few great guides on here which you should definitely take a glance at.
Generally the fundamentals are there regardless what level of club you start as. Picking a club you have knowledge of and know your players strengths I think helps, and know how far you can take that club with the finances and structure it has in place. I've seen too many FM players who have broke the bank trying to take a team like Norwich to the top and end up in financial ruin! Bring in a solid back room (this is the only true way you're players will ever develop)consider who you play during pre-season (whether if you're a small club you want me to increasing finances by playing big teams, but possibly damage morale with heavy defeats,) whether you want to give youth/reserves a chance to shine, or just get match time and fitness under your first teams belts From that you want to be looking to bring in a select few signings, I tend to find maximum three a window so you keep the balance of your squad, but some people will argue that.
Have a look at the guides that are about on the discussion forums, they are a great help even for the most experiences of veterans. If you ever want any tips, feel free to PM me and I'll lend whatever help I can.