advice 2.0: now with more help!
Go to LOTS of low-level tournaments. People have managed ratings of 1700 just by attending loads of Battle Roads and City Championships, when the cutoff is often around 1850.
You cannot qualify for Worlds without playing high-level tournaments, simply because you need the extra points - but you're not likely to get the top cut invites, so you should play lots of low-level tournaments to give your rating a big boost, too.
For me, I'm not gonna qualify in a million years. I have to go play Grinder, which should be fun anyway.