I went through this and still do. I feel as if everything has to be perfect before I start and that invariably leads to delay.

Really the best thing to do is just put something out there. It's not going to go to the top of page 1 so nobody but you will see it and you can work on it slowly, making changes and adding stuff so that by the time it gets to #1 it will look good.

Go on give it a crack.

Choose your favourite interest to start and the one question you would want answered in that niche. Research the answers to that question and write them down. You now have the content for your first niche blog.

Have o fear we have all been where you are and we still go there occasionally.

Pick your ultimate favorite and go with that. Then in time when you're ready you can start a new site. I see way to often new people try two and three sites at once only to be become very overwhelmed and discouraged.

It's okay to make a list of all the things that interest you, but then force yourself to put them in order. Sit on that for a day or two then review the order to make sure you still like it that way. Then start building your site based on the top item. It's okay to keep adding stuff to that list, but only work on one site at a time so you can learn the process and get one done. Don't let the Shiny Objects distract you from that goal.