I started by thinking up a game that I want to play myself. Something that I feel is missing from the available games. Then I started writing down just the mechanics that would be needed to make the game such as how the player will move or what interaction the player will have with objects. Then from that point I began making several small test projects containing a single mechanic and stand in graphics (black squares and circles). Once I have the mechanics all worked out I set out to merge them into a single project one mechanic at a time. Then I begin putting in production graphics and implementing them as I go so that I constantly feel my game come to life. Then I go through another phase of extensive testing to try and break my game as a player might and correct any bugs I find. Then I begin the part I like the most, which is polish. Special FX, animation touch ups, graphical enhancements, flavor text, lore, everything that might give a player a sentimental connection to the game.
I manage my project time by establishing a schedule and sticking to it whenever possible but with a kid a lot of time that can be impossible and you will have to delay until the next day or so but always try to keep it. Here is mine (sorry if this seems a little silly):
Monday: Workout, Gaming
Tuesday: Cooking, Workout, Gaming
Wednesday: Developing, House Cleaning
Thursday: Shopping, Workout, Developing
Friday: Workout, Gaming
Saturday: Cooking, Family Projects/Trips, Developing
Sunday: Family Projects/Trips, Developing or Gaming
I have found that the trick here is to only develop as many days as you have planned for and not more, which will help with preventing burn out and I always make up my missed dev days by overwriting a game day where needed.