In a typical startup, The Management (even if its just you) often wants to do lots of different things at the same time. This is difficult, because you have limited time, people, money, and other resources to carry out all these initiatives. Here are some ways you can get all those projects under control.
Create a charter for each project. This is a simple 1-page document that simply describes why you're doing this project (the business goals). It also lists the project's Sponsor, the person you go to for money or resources and whose neck is on the line to get this project done. The charter lets everyone on the team know what the project is all about, and is the guiding force in making decisions. All the work done on the project should support the reasoning in this document. It also includes success criteria, so the team knows what the desired outcome is -- whether to lower the amount of time spent waiting for customer support, or increasing revenues by providing a new paid service for your users. This should be quantifiable and measurable, so you know whether the project has achieved success. ...