I can only speak from past experience, as I have only been making music again since last summer, and even then only a couple of songs so far have "proper lyrics".
In previous bands I've found three things that work...
One is simply to binge listen to a lyricist you admire (for me that would be the likes of Rozz Williams, Aaron Stainthorpe, and Juha Raivio etc.) and just get into that vibe before putting pen to paper.
The second, which I use when I'm stuck, is to have a notepad and have each page as a theme - kind of like a sketchpad - and then take a word, or phrase, even the title of something and just keep adding to it. Don't worry about it making sense at first, and don't think you have to get it all down in one go as you can come back and add to it etc. Hopefully after a while you will see bits that naturally join together and it will form up nicely.
The final one is to take some text (from any source) and put it into the Lazarus Corporation Text Mixing Desk: http://www.lazaruscorporation.co.uk/cut ... ixing-desk
and go full Bowie / Burroughs on it.
If you're finding your lyrics are coming out too complicated, try looking at what it is you're actually saying and be merciless with cutting back on things that are in the text but distracting from that - Think Ernest Hemmingway's The Old Man And The Sea - cut to the bare bones and be direct with your language.