Pomodoro never worked for me since I work best when I get into flow and keep going for 1 to 4 hours. What I have found helps is planning as much as possible up front and dedicating time to do so. I braindump everything then when that’s exhausted I rewrite it in a structured way and add detail, breaking it up into sections and gathering resources I need, then I make an exhaustive todo list of tiny steps in chronological order and I mean really tiny steps with concrete outcomes. Then when I start working I just follow the plan and since I’m very familiar with it by this point I don’t have to refer back to it all the time but I do make sure to check it in order to stay on track usually when I reach a point where I’m uncertain of what to do next. I also add to the document when necessary.