There is no 'One' way as the correct way to smoke a turkey.
But there is a general consensus.
Have to have an accurate, quick read, digital thermometer to check the meat temp.
As stated always cook by the meat temp, not by a stated time as this is not an exact science.
An accurate grill temp thermometer is a plus,
You have to have a good idea of what temp you're cooking at.
Spend $50.-100. and buy a decent digital with dual probes, one for meat temp one for cooking temp.
If you have the money, a great Instant read meat thermometer is the Thermapen.
I'm another one that would cook at 250-275', prefer the higher temp.
I average 20-25 min per pound at these temps with a spatchcocked bird.
Spatchcocking (butterflying) will speed cooking and cook it more evenly.
I spatchcock all whole birds except Cornish Game Hens.
Applewood is great for birds, I also like Pecan & Cherry for birds.
I think it is possible to over smoke a bird and only use smoke for the first 1-1.5 hrs or 140'.
Brining is an option, sometimes I do, sometimes I don't, generally it is a matter of if I have the time, ingredients and a bag.
Another option I like is a herb butter under the skin, like brining or injecting it helps keep the meat from drying out and imparts flavor.
Don't worry about a prepared Rub per se, just season it with what you have and like and start shaking it on.
I would get happy with salt, onion powder, garlic powder, rosemary and thyme.
If you want to some spiciness, a Cajun spice mix instead of the S,O,G it has those plus paprika, cayenne and some others.
Again, number one rule for delicious, tender and juicy meats... Cook to at least the proper minimum internal temp and/or target temp.