As others have said, flexibility is the key - but not always in terms of looking 330 days out. It helps to have the flexibility to go 'next month' - as seats will start to open up.
Some advice from my recent successes: Try searching from either EWR or IAH to either GUM and/or your final destination. As someone mentioned, it sometimes helps to search segment by segment - the problem with this however is Micronesia.. CO has 'special' Micronesia only rewards so that if you search GUM-TRK you may see first available - however it most likely will not be compatible with the BF award from North America. And really, if you you can't get first from GUM to wherever - it's no big deal at all (with the possible exception of CNS). So, the trick is just getting to GUM. If you really want to experience BF, you'll want to route via NRT instead of HNL. (For that matter, you could even opt to fly NW). I was surprised at how much std BF availability there was when I started looking in MAR for the Jun/Jul timeframe - lots of seats, even weekends. Finally, even if you can only get BF as far as NRT or HNL, as an elite you can be waitlisted for BF/F segments to GUM. We had no problems getting into BF, the agents in both NRT and GUM seemed very knowledgeable and helpful (dealing with the csr in CNS for the first class seat we were entitled to however was another story...)