Blogspot all the way! The pre-made templates are good, but you can customize them a bit if you're willing to play around with the hTML code-- see my blog in signature line for an example-- the background picture is a photo I took. It's not perfect but then I'm no computer whiz either.
Personally, I'd love to read a blog about yurt living! The most important thing about keeping a blog is to update regularly-- at least once a week. Even if you're just writing it for yourself, it is so useful to get into the habit of writing with regularity. I started my blog in September 2005, almost 2 1/2 years ago. It's nice to be able to look back at previous entries and see 'where I was' at that point; what I was thinking, what I was doing. Life changes so fast, even when it feels stagnant; journaling is a great way to sort of throw down an anchor and record what is going on right this minute. Regular contributions also help if you would like other people to read your blog-- it's what keeps readers coming back. The more regular your writings, the more likely folks will be to come back and check. (There are some blogs I only think to check every month or so, because they don't write very often, and some that I check as part of my every-day routine.)
The only other thing I'd suggest is to write about everything. I mean, obviously keep private anything that's too private to publish (I generally never talk details about work for the obvious reasons, or sex, or arguments with the DH, etc), but even if your blog is about living off the grid you can still incorporate a lot of other parts of your life into your writings. It makes the blog more well-rounded and interesting, and if you're writing primarily for yourself, it gives you a better record of your own life. Blogger lets you create categories and "tags" or labels for posts, so you can tag every post that includes, say, gardening, with a 'gardening' tag; same with everything else. That lets you write about a lot of different things but still have the information categorized by subject; for example anyone visiting my blog could very easily read just the posts that deal with miscarriage. Or with Harry Potter. Whatever.
The only other thing I can think of-- and this is from reading a lot of other blogs-- is to aim for timelessness. It's like choosing a username here at MDC: how many mamas have names like "mama2two" or "proudmomtoSam" or "tryingfornumberone!" only to have more children, or get pregnant, etc., and make their username out-of-date so that it no longer reflects their situation?