Agile is a great cue ... I personally went over to using SCRUM for working on my personal projects (it makes sense even as a lone wolf).
You write your product backlog first (it kinda is a business concept). I usually write it with user stories that I can simply copy to the sprint backlogs later.
A month is a little too much for me. I think two week sprints make more sense.
Every two weeks I make a sprint review and a sprint planning "meeting" ... I meet myself I guess ... decide what stories I want to work on, estimate the effort of each story, define the activities in the story and estimate how many of the stories I can actually solve in two weeks.
You need a "definition of done" for each story ... well guess you can check out the wiki article.
Each day you can think about your progress and ask yourself if you are on the right track.
In the sprint review you can check how fast you actually work ... you can write your problems down in an impediment backlog ... if you think that helps with the awareness for what problems there are.
The great thing is that you can leave everything out that you don't like if you do it for yourself ...
but ask yourself twice if it is a smart idea. Try to figure out what problem SCRUM solves with the rules and think about if you have a tendency to stumble into those problems.
And when you work on the product backlog you can already get a feel for how much work will go into a project ... you won't be simply overwhelmed later - it will be at exactly that point
It helps even if you plan to take a break. The documentation will be useful when you try to remember where you left off, what your exact plans were and what you have already done.
It helps with the "many ideas problem" ... after writing lots of backlogs you get an idea of what those ideas mean ... and it will be easier to decide which product's stories you want to tackle in a sprint.