I think about what is a minimum viable product.
You need something unique, that's a force multiplier, that lets you punch beyond your weight.
You have to spend a lot of effort on things you might hate, like documentation, marketing, fit and finish, and installers to really make something people can pick up and use. But that's part of the MVP; either push through the pain or get help.
Don't Learn just to Learn. Say your day job is PHP and MySQL and you're a machine at that. If you don't know any Scala or CouchDB, it's not a good idea to switch to them, unless you've got an excellent reason or enough cash in the bank to quit work for two months because you'll waste that much time thinking about how to look up the length of a string and stuff like that.
Use project management tools. Bulleted lists on notepads, in text editors, index cards and such are powerful. (Today's "cloud" systems for project management are painful to use because they don't have the tactile immediacy of paper systems -- overcoming that is an opportunity)
Stop doing something. There are only 24 hours in a day. To free up time on activity A, you have to stop doing activity B.