I would also add that every lake is different. Some lakes you need to fish really deep like 90 feet and then others less than 20 feet. Some lakes they are very aggressive predators and will take spoons jigged without bait, at other lakes they seem to be more like scavengers and just want bait presented slowly or not moving at all. Seems to depend on what kind of fish they are eating. In the kokanee lakes spoons seem to work better.
I would also add that they are a 'here today gone tomorrow' kind of fish. You can catch 4 one day at a spot and you think you have found a great burbot hole, and then you go back to that same spot and get skunked 3 times in a row! Can be very frustrating. Also at some lakes they seem to congregate and you can sit in one spot and fish, but at most of the lakes I have been successful at you need to move around and cover water.
Also - try new lakes! Almost all of the medium to large lakes around PG have ling. You will probably do far better to explore and find your own ling spot than you will to go to Eaglet or Norman or one of the other heavily fished ling lakes. Lots of guys on here don't like to admit it, but ling are very sensitive to over fishing and some of the lakes that used to be good suck now.
Good luck out there!