Mae it's really not that hard. All you need is 1 good run at any tournament lol.
In my First TT year all I did was reach 3 Challenger SFs and avoid having to play Qualifying at challengers.
2nd year I reached 2 challenger finals, which got my ranking high enough to sneak into RG and wimbledon MD somehow, where I won 2 matches at each.
Made sure I got into USO, and I reached the QF there. Then it's ATP MDs and you just have to play solidly to stay in the MDs