"What blogs are popular in these times?" - Well, first of all you should write a blog about something you expertise in, it's very important to make your content interesting and captivating, if you want to attract more visitors it's also important to make it relevant to that arena you are aiming at. "How can I promote my blog?" - Social networks is the best means for promotion. There are lots of social bookmarking tools as well to help your content get spread.
Just like you I'm new to blogging. Myself I'm leaning towards Wordpress. I'm starting up a blog to kind of tell an ongoing story of how I'm learning to program graphics and animation and I will be linking it back to my website on robotics. The comments here on this thread saying to be in it for the long haul are salient - it does take time! Last month I got close to 200 unique visitors/~800 hits, and that's taken about 6 months to achieve. I think I got like 3 hits in my first month. I won't be running away from it though - I love building and programming robots and writing about robot ideas, but it's tough to be productive day in/day out and have material to write about when I've got a full time that has nothing to do with programming or robotics! It's about the journey though right? Best of luck to you!
I just started, but so far I am using blogspot.com. I guess I may give wordpress a try though, since I see it mentioned more on these types of sites. Blogspot has a lot of useful tools as far as watching traffic.