Walking path map to Bila Beach. If you want a long-tail boat from the ferry drop-of
From Bangkok to Koh Lipe
Bus, train, air plain or minivan.
There are many ways to go to Koh Lipe.
The easiest would be to fly to Hat Yai and from there catch a minivan to Pak Bara and from there you just buy the ferry ticket to Koh Lipe...
Or if you go slow, catch a sleeping train from Bangkok and save the money of one nights accommodation...