Solo commentating can be pretty nerve racking, especially once you realize that at the time of recording the only person you're talking to is yourself.
A helpful thing to do is just get a general idea before recording of what you're going to talk about. You don't want to write a full on script, because you'll get fixated on saying what you wrote down, and if you mess up on the script you'll likely stumble. If you have nerves about coming off as boring you definitely don't want to try and wing it, since you'll likely end up rambling.
What I mean by getting a general idea beforehand is by knowing what you're going to be going through while recording your video. If you're playing a game you're familiar with, talk about things you remember when you played the game in the past, like how you like the song to the stage you're on, or how challenging this level was for you the first time around.
If it's a game you're new to, try to focus on talking about the things that are new to you.
Some other things to avoid that turns viewers off is complaining, recording while you're bored, or speaking in monotone.
Once you get enough feedback and feel comfortable recording while commentating, winging it becomes easier and you can start talking more naturally. Also, if you have friends commentating with you it becomes a cakewalk.
I will say that I personally watch a lot of the LPs here that aren't pokemon ones. I liked the sim city one that was done (made me re-get the game) but I never really post as I have no idea what to comment.
That's a very good point, and I think you should play Digimon World. It always make recording LPs much more fun when you're playing an old favorite of yours, and even better it's a game you don't see being played by LPers very often.
Also, you're point about posting a comment on the thread is another good point, showing that LPers have to give the viewers something to respond to in order to receive feedback! : P