Sounds like you know most of the important pieces but lack the confidence to jump back into the fray. For more than a few years I have been in love with the Lean Startup approach and the MVP. There will always be pros and cons to any approach, but this methodology still packs a lot of horsepower. I have built several companies in just 90 days. My efforts are turbocharged now with this simple approach. More thorough plans are possible than otherwise might be the case.

I use the Lean Canvas by Ash Maurya as my template for any new idea or project that I need to explore in detail before deciding to jump. Then I live in it and share it with others as needed. Those nine blocks in the canvas are pure gold if approached with a few pieces of common sense in hand and if (very big IF) you are willing to take some direction. Look it up at leancanvas dot com and if you want some insight, schedule some time and let's make it happen.