Organisation is an important thing to keep in mind. It helps with motivation. Separate the month in different periods. For example, during first week you work on concept and design, the second one you work on making a small demo, third week you expand the game to your taste, and the last week you polish the game. It's also a good thing to set up goals and to have a clear idea of what you want to include in the game for the end of the jam. This also helps with scoping, since you can easily overscope because of the jam's duration.