Don't do it.
First of all, let's be honest here, you probably suck. The odds are with you, since most people suck, are idiots or complete and total nincompoops, most likely you are as well. And no one wants to read your drivel. You will only set yourself up for failure and seriously, do you need more of that in your life right now?
When was the last time you had an original thought? One not based on a pop culture reference? I thought so. Been awhile, huh? People that read blogs expect to read compelling, interesting and original thought at least once a week. That is a hippo ton of expectations. One that will hide barely under the surface only to jump up and chew your leg off in a way that makes it impossible to ever face your few friends again, cause you got your leg chewed off by a giant pink water pig. Don't get your leg chewed off by a giant water pig.
Secondly, have you seen just how many other blogs there are?! I mean, good grief, there are dozens and dozens of really, really good blogs out there already. What can you hope to add to the general gestalt that is worthy of the discerning reader? I can tell you... nothing. So why bother? Put your time into finding something to do that no one else is doing and make it your own. If you need suggestions for that you've come to the wrong place, but I bet someone is writing a blog about it.
Lastly, blogging will ruin your already pathetic life. Like all you need is just one more reason for chicks to ignore you. If the comics, Star Wars figures, MMORG game play haven't already done enough damage, blogging about it will be the proverbial broken camel back. Do yourself a favor and put your time and energy into things that girls actually appreciate, like having your own place, a job, things like that.
Blogging will destroy you. You are not tough enough for it and it'll eat you alive. I'm just trying to warn you. Someday you'll try to quit, to hang it up and you won't be able to. Trust me.
If none of the above has convinced you yet, one last warning. I don't want you to blog! Good grief, the last thing I need is another blog on my reading list. In the name of all that is Holy and good, don't do it. Please.
You're going to aren't you? Fine. Don't say I didn't warn you.