Domain name and keyword relationship

ok, folks. Some of you know that I've it a concrete barrier in my progress here, and have had to take a 'thinking chair' break (you know that every project, whether it's solving a home-maintenance issue, writing a story, sewing a gown, or painting a room requires a 'thinking chair', right?). I've been doing a lot of thinking, and have somewhat been able to jump-start my creativity and focus. But now, I have another block and need help.

Specifically, I need domain name help. I found an awesome kw phrase (long-tailed-keyword), with a domain available....and it's something I'm quite interested in acquiring. So - when we find a phrase that has awesome search (over 7k) and next to no competition (17) - is it a good idea to buy a domain with that kw?

I am a reader-bee, a learner-bee, much more than a chore-bee: I only say this to emphasize that every day - yes, EVERY DAY - I learn something. I'm arrogant enough to think that others might get a kick out of reading about my new learning. Maybe not - but - hey, a blogger has to start somewhere, right?

My most profound hurdle at the moment is getting readers to stay interested. I need, and I mean NEED, dialogue in order to spark my writing. Without traffic, it feels like I'm talking to no one. When I get comments, I always respond, and try to start a conversation, but it doesn't work like on 'forums', where people are already there and looking at what you are saying.....it's been a difficult adjustment to make, because I thought my 4 years of forum activity (and large number of followers and respondents) would translate easily to having my own site.

It doesn't work that way, though. Doing blogging on your own site depends on readers finding you via whatever means.....when on a forum, they see what you wrote whether they want to read it or not.

ANyway - that's where I'm befuddled. My forum activity was prolific, and my threads gained me front-page rank several times. Why is SEO so much harder than that? Well, that's something I'm still learning. How to pull in readers via social & search when you are an unknown is a very slow/difficult process(as we all have learned here).

I digress, though. Sorry. So - here is the current confusion I have:

A few months ago I found a long-tail keyword that had incredible 'results', and bought a domain by that name, but it turns out I'd have had to do an incredible amount of research to get it off the ground. So - it sits there languishing in 'construction mode'. (Oh well. I guess I could offer it for sale.) I have other topics I'm more interested in than that topic (how to for guests), so - meh. A problem. Do I REALLY want to start a new learning campaign about how to do things for guests, when I only know a few of them? No. I don't. I thought I did, but I don't, as much as I'm interested in anthropology, social structure, and human behavior, I don't have enough verve right now to dig in there.

BUT -

Today I thought of a new section I'd like to add to my two site(s): "today I learned".....a place for a 'blog' that just talks about my life, my own journey, and what I've learned in my areas of interest. EVERY DAY I learn something new, and I thought it might be a worthwhile thing to put out there to get readers.

So - the long-tail keyword (which, for newbies, just means a "key phrase" - a kw with more than one word) - "Things I have learned life". It has almost 7K searches per month, and only 17 competition. But, it's not exactly 'brandable' as it is.

I'd like you all to help me determine if it is worth the investment in the domain (which is available as a dot com and a dot net) - 'thingsihavelearnedlife'....or whether I should just make categories in my existing domains with that phrase and put them on the menu.

Your thoughts will be greatly appreciated.