I have trouble getting started myself, though I find looking up tutorials for similar games to be a good starting point. Especially the "Make a complete game" ones, they're good at getting into the right mindset. Regular programming isn't that different from games when you know how to look at it. A lot of strategy games for instance are just spreadsheets with a complicated GUI when you get down to it.
Actually, a good way to start might be to open a document or a spreadsheet and write down all the things you want in your game and then work out what variables each of those will need next to them. Getting down what you can to start with can help you figure out the direction to take, because that way you kind of reverse engineer it from the idea backwards into what code will be needed in order to use the variables.
Hope that helps