I know this is an old thread but I like thinking about this kind of stuff and wanted to add my own system in hopes it might help someone else or could be refined through criticism. This was taught to me on a Mormon church mission as a way to optimize productivity and, since it's heavily focused on tracking progress through measurable key indicators, it might need to be streamlined for some.
VGP
Vision: start with the image you are trying to create. Self explanatory but imagine what kind of life you want. What it looks like, the kinds of behaviors and activities you engage in, the kind of person you are, etc. The clearer the vision, the better.
Goals: specific milestones you need to accomplish in order to actualize the vision.
Planning: the step by step process to accomplish the goals you've set. I used to get very detailed here but I've simplified a lot since reading books like atomic habits.
Time management: VGP is used to get organized and clear on what you're trying to accomplish. Use whatever daily time management method works best for you to make steady progress. On the mission, we would have daily, weekly and monthly planning sessions, but I would also add maybe a annual review for the bigger picture (i.e., if you have a vision for where you want to be in your career in 5-10 years, you will break down what progress looks like for each year). If everything's fleshed out well enough than you should be able to create key indicators that can help you measure your progress. Or if you prefer a different approach, you can develop specific habits that will turn you into the kind of person that achieves the vision.
We would do a planning session at the end of every day, where we review the day and see whether we accomplished the goals set in the previous planning session. We would use time blocking and set goals for key indicators, such as how many lessons we wanted to teach, how many new people we would contact, new appointments set up, etc. LDS missionaries are firm believers in the adage "that which is measured is managed." We would give ourselves positive and negative feedback. Why did or didn't we achieve a goal. Then we would plan out the next day with a renewed focus to accomplish the weekly goals.
Daily planning is done with the weekly/monthly/yearly planning on mind. In weekly planning sessions you review the monthly and yearly plans, evaluate how the previous week went and plan out the next week with all that in mind.
If you don't have much time outside of work or other commitments to devote to side goals I don't think it's any more complicated than using what time you do have in a productive manner, or creating the time somehow. Just depends what ones priorities are, as AWP said. Some goals require sacrificing in some other area.
This might be too rigid an approach for some. Planning out your day only takes 10-30 minutes depending on how detailed you want to be (we would plan out the day, make altrrnative plans if things fell through, whatever. No excuses. If we had the goal to teach one lesson and the appointment we had falls through, how are we still going to accomplish that goal? It was always much more productive if we planned our day or in as much detail as possible). But my point is, it doesn't have to be that detailed. This is just what had worked for me in the past.