The biggest difficulty for the solo/tiny team developer, IME, is getting spread too thin - brain drain, whatever you want to call it. Because there is too much work to do, even on simple projects.
So, when it comes to software, technicals, etc, my goal is always to keep it as simple as possible. Limit the amount of new stuff you have to learn so that majority of your time is spent developing and iterating on player experiences. If long periods of time are spent solving technical or organizational issues, you’ll lose momentum and development will become a test of your will rather than a journey of bliss and discovery :).
For daily/weekly/monthly checklist , Trello is the simplest solution, so that’s what I use. Don’t go overboard trying to plan everything though - I just keep a running tab of stuff doing right now, stuff coming up soon, and stuff to be done later. The goal is only to make sure I don’t forget things and can reassess my priorities each morning before starting work. Anything beyond that becomes a time sink, so I strongly recommend don’t get crazy over-engineering your organizationals.
Before I start any new task, I got in habit of saying out loud WHY I am doing it, and I review my priorities written down on Trello. I also define a backstop - something to let me know when I have satisfactorily reached the goal, so that I don’t go too far beyond it and waste time. All of this helps avoid time wasted noodling, which can become a form of procrastination.
For daily communications with your teammate, discord or google meetings is great. GITHUB desktop is a very user friendly app for version control.
Assuming you haven’t made a lot of games on your own already, I think it’s better to not try to plan beyond your capabilities. In other words, a plan depends on knowledge to be useful, but you don’t know everything yet, so your journey then is more about discovering unknown things. So don’t try to conform to a rigid plan, but rather develop a way of continually reassessing where you are, where you want to go, and have regular reassessments to reconsider priorities in light of new knowledge gained.
Completing and publishing a really bad game is much more noteworthy than almost completing the worlds greatest game. So for the first couple projects, I’d set highest priority on finishing, above all else.