Prioritizing Everything

"Where's your calendar?" a coworker asked me this morning.
"My what? Oh, ummmm..... "

I am one of those people that gets "the newest greatest idea" every 10 minutes only to discard it the next day. I get an actual great idea a little less frequently but I'm at a point where I have a lot going on and need to prioritize things. Being the sort of person that decides things last minute, gets distracted easily, and changes my mind on a dime, you can imagine how hard this is probably going to be. It's important to me that my side projects don't get in the way of my regular job and vice versa but being a modern sort of girl, there's a lot of blending going on. I realize that some of these ideas are probably pretty ridiculous (#7: Make or work on a zombie movie. I mean come on what am I, a 15 year old boy?) but some are just difficult to manage (dear blog: you are not allowed to take over my life).

Here are my options.
1) Make a list. This could be a to-do type of list and I could sub-category into: important, pretty cool but not productive, and probably not going to happen. I could envision this list going on forever and ever though. Simply writing things down more doesn't actually get anything completed.
2) First Come First Serve. Just do the first project straight until completion before I start something new. As a chronic un-finisher of things, this might be beneficial for me.
3) Get a Damn Calendar. This would have to be slightly more mapped out than I'm normally comfortable with but I was thinking of designating days and times for certain projects. The downside to this is that every time I sit down to do some writing....... I just sit there. At 4AM, I pop up in bed and MUST get something down immediately which is going to be a problem for the whole calendar thing as I don't plan to designate 4AM for anything but sleeping.

What's the best way to organize and prioritize?