Take a photo, write a chapter, post a blog, do something new, once per day for a whole year.
That's a 365 project.
In a nutshell, it's doing something once per day for an entire calendar year. Sounds easy? Well... no, not really. It can be pretty hard to discipline yourself into doing something every fuckin' day of the year. In fact, the biggest killer of 365 projects is "oh but it seemed too much like a grind and I got bored and I don't wanna do it any more".
So, obviously, step 1 is to pick a subject that ain't gonna get boring. Or grindy. And keep it short and simple, so you only spend 5-15 minutes per day on it. I myself picked "post a photo of the people, places, things and ideas around me, every day in 2011". Only on two days in July did I lapse, and this was understandable as I had had my wisdom teeth out at that stage. But I persevered. And I digress. Moving on.
Step 2 is to decide: are you a sharing person? Do you want this to be public or kept only to yourself? Blogs are public. Diaries aren't. Pick your favourite medium carefully because it's generally best if you keep it consistent. To help decide, try these: How much recognition/fame do I want? Who do I want to see this? Does this project work with this medium? Does the medium require the wearing of pants?
Step 3 - pick your starting date. Which will also be your ending date. Of sorts. January 1 is popular and easy. And it makes the project feel like a New Year's resolution, which you won't wanna break. Bonus! Ensure that, if this project needs lots of prior planning, that you pick a day a bit further into the future. Don't start a project on Day 1 and suddenly find yourself still planning stuff on Day 8, because you've now already missed a whole week.
Step 4 - do the project.
Step 5 - don't give up and don't break!
Step 6 happens exactly one year from the starting date. Congratulations! It's done. Now what? Archive it, keep it as a memento, publish your findings, scream it from the rooftops. Anything, as long as you keep a hold of that project. Because 365 days is a memory chest, whether you want it to be or not. So unless you're the sort of person that hates memories, keep it safe.
"It's a leap year. What do I do?" Then it's not a 365 project - it's a 366 project. I'm sorry, but I've never done one of these, and so I don't have any advice for you. At all. None. Not even a helpful step-by-step. You'll have to ask someone more experienced.