How to get motivated for and plan my pet project?

I am a student now and I have been coding from the last 3yrs. I think I am am good at it. Made some awesome apps where I worked and interned. (on java), 80% of 24hrs is spent doing something for my school project or trying to learn some random thing. I also made a website which has 1000 odd hits/day which was build using php 3yrs ago. (pretty simple). Now, I have been playing with Rails from the last 1 month and trying to upgrade my website and in that process learn Rails too. I am also pretty much motivated and I know if I get things rolling, I will work on it day and night. But my problem now is, when I start with rails and try to make something, I get stuck at some very basic things which are like good UI, JS etc. I am not able to get a start. I think it has primarily 2 reasons: 1. Lack of Rails know how, 2. procrastination So, any suggestions? What is a good way to go about it? How should I divide my project?