Keep it in me head mostly.
Kind of made a list in my head when i bought the car of what needed to be done to the car to have it sorted mechanically...and decided on wheels and suspension set up that was it really just put it In order of most important bits first.
ive got a kind of goal for what i want to do by a certain time like exterior interior.
if its mod wise and if a certain part pops up before i need it and cash is available ill grab it and put it by till im ready.
If its something i can do myself its a big help because i dont have to factor in labour costs or borrowing a car i can do it at my lesuire.
If its a thing thats important matainence wise like brake
pads tyres etc it gets priority and bumped to the top of the que.
Ill service it at its regularly in between everything.
Always get ideas from others aswell and change my mind about things so lists would be a few pages of scribble for me im afraid as there constantly changing so I suppose I'm a bit random