I smoke a lot of fish, mostly stripers, they are my favorite. I take the skin off and cut out all the dark meat (personal preference) some people leave the skin on. I cut large fillets into chunks, makes them easier to take off the grate without breaking apart. Someone mentioned them falling through, I don't have a problem with striper, the meat is pretty firm. My grates are coated, I spray them with Pam. When the fish is done I can remove it with a little nudge with a spatula.
For the brine I use about 1 cup sea salt or kosher salt and 1 cup brown sugar to a gallon of water,. I soak it in the brine overnight.
Whatever you do, if you are using a water pan DON'T USE THE LEFTOVER BRINE FOR THE WATER!!! Don't ask me how I know this.
Rinse the fillets after you take them out of the brine and
let them dry, this is important, they will get sticky, that is what you want. Now is the time to season them, you can use whatever rub you like, I sprinkle the fillets with garlic powder, lemon pepper and blackening seasoning.
For the wood you can use hickory or mesquite but that will give it a stronger taste, a little bite. Lately I have been using apple which makes it a little milder and sweeter. Depending on what type of smoker you have (mine is propane) I prefer chunks to chips less flare ups and last longer.
I try to adjust the heat to around 150 degrees for the first 1-1/2 to 2 hours then about 200 for an hour or 2 depending on the thickness.
Here is a batch I did a few weeks ago.