Code effort is typically about 20% (+-10%) of a project budget. Focusing on getting code correct is pointless, theres 80% of the effort that you have not addressed, so getting perfect code managment still leaves you with only 20 of the work done.
What if your project has no users? What if it's perfect but published one week after "Acme Patent Trolls" file for a patent on the idea, and it turns out to be the next Facebook?
Look at the following standard project lifecycle issues
Requirements, Design, Code, Test, Integration, Deployment, Defect tracking and correction, requirement change management (enhancement requests). Release plans, resource allocation (how many hours are day are you planning to, and will you actually do on the project), Legal (Freedon to operate) etc.
If all the above are in place, even very bad code will be successful. If none of the above are in place, the best code will fail.
I am not a betting man, but I would put money on it your first "big" project will fail, in many and varied ways you can't imagine. Don't worry, go ahead and fail, learn from it and do the next. Not starting would be the real crime. If you do succeed first time, you have a solid career in business management, not programming.
So to answer you question, put away the software tools, and pull out your "business planning" tools. Work out WHY you are doing it, for WHO then WHY and WHEN they want it. (You can be your own customer, but do the exercise anyway).
Write this down in a "Business plan" and build from their.