Keep going.

It's normal for your first stuff to not be very good - You'll only get better by working at it.
Reading other people's lyrics, poetry, books, basically any kind of writing will improve yours, but the best way to get better is to just keep doing it.

I suppose you could try to analyse exactly why it sounds stupid - And that way you'd have specific areas to try and improve on.
A really good technique I've found, albeit a little time consuming, is just write what's in your head and just let it roll onto the paper. Don't worry about making it sound great, just get it on paper. Essentially, sit down, and just write your worst, lol. Once you have all your ideas down, call that your first draft.

Now, write it again, and fix a little as you go. Reading over it again as a whole will help you straighten out the parts you weren't wild about in your first draft. This is your second draft.

Continue as many times as you need until you have it shaped into exactly what you want. It might take you 4, 5, 6, even more drafts to get what you want, but I find that it really works well.

The whole idea is that you can't sit down and expect to just write a hit song on your first try, and you're inevitably going to let yourself down and get discouraged. But, if you sit down, and tell yourself to basically write the worst draft you can, it can only go up from there, it'll give you a little motivation knowing that you sat down with the intent to write the worst you could, and you finished it, completing your goal. Then you next draft, make the goal to just make it a little better, and a little better each time you re-write it.

Like I said, time consuming, but well worth the effort.