If you really want to become awesome at making games, you need to play a ton of them. As a game designer you need to understand games from a psychological and technical standpoint. Can you outline the technical aspects that make a good game? What are your some of your favorite games of all time, conversely, what are some of your least favorite? Take 15 minutes and list your five top games. Think about what makes them good games and what makes you want to play these same games years down the road. Now do this with the games you don’t like as much. Did you become disinterested in the game too soon due to in inappropriate reward system? It’s good to know where your inspirations come from so you’ll know what game to create and even better, what games you want to steer clear away from.
The right inspiration also helps a ton. It’s important to document all inspiration prior to creating a game. That way you can easily go back and locate art styles, screenshots and links that give you good ideas for source material. No need to create an elaborate game design document if you’re a one-man team. Instead, focus on getting your ideas together. If you can, try to jot down a couple lines of copy about what you like about the items attached. If not, it can sometimes be impossible to remember about what you liked about said materials in the first place. Attempt to write down your ideas before you delve into the most technical aspects of creating your game. You don’t want to waste too much time creating something that will leave you frustrated and very unproductive, so don’t wing it. Play a lot of games, and plan for success. Your career depends on it.