First you need to do this,
Consider what style of music your band is going to be playing. Number two look at other bands in that style or genre. Look at the lyrical stylings of them. Decide whether or not you wish to write lyrics at or around their level in a similar style or if you wish to diviate from it and do something new.
My advice is to get a theme nailed down for a song and then write lyrics that are symbolic and meaningful to you and either make them simple or complex to your writing ability or liking. Also i would suggest looking up meter and rhyme poetry styles so that you can get more creative.
Also another tip never repeat the same word at the end of two lines, personally i think that makes lyrics really lame like the writer couldn't think of anything else to say.