One technique which I really like to use for prioritizing software development projects is the MoSCoW approach.
The capital letters in MoSCoW stand for:
Developers love to write code. However, you will save lots of time in the future if
before you start implementing the software project, you prioritize all the requirements according to this simple method.
Focus your time getting all the MUSTs in place, and thoroughly testing them. Only after they are in place, focus on the SHOULDs. If you have extra time left, go for a walk, get a Starbucks latte, sit back and then think if you could squeeze in the COULDs.