Every Puppy Has a Little T-Rex in them at first
I have two techniques I use that have served me very well. Like with everything else in puppy training, consistency is key!
My first trick is toys. Toys everywhere for the first month or two. A toy ALWAYS in reach. I keep these mini ropes everywhere, even in my pockets, they are perfect for a puppy, . Every time I engage my puppy in play, I pop a toy in their mouth. They still get to bite, like they want, but its not on me. Of course the occasional puppy bite sneaks in, but I just sternly, calmly say "NO", and pop a toy in their mouth as soon as possible, and then resume play. They learn very quickly what is ok to bite. It is so effect that my older dogs will hardly play without something in their mouth. If you look at them with the tiniest hint of "lets play" they run in search of a toy to hold, usually one of these fleece ropes. Go to Mothers Merchandise, I sell these ropes for a great price. They are more costly than the typical rope, but they are safer, stronger and last longer.
Often when learning to take treats, a puppy will take a piece of your hand with it. Puppies are very food driven. I assure you the puppy doesn't want to bite your hand anymore than you want it to, it simply gets caught up in the moment. The key is to teach your puppy to slow down. I take treats and hide them in my hand, so the puppy can smell it, but not grab it. This forces your puppy to use their nose in search of the treat. I slowly open my hand as the puppy searches and eventually they find their prize and get to enjoy the fruits of their labor. The first couple times might be chaotic and ruff, but after only about 3 times doing this your puppy will catch on, and start slowing down. All my girls take treats perfectly. I have one that takes them so gently, you have to practically push it in her mouth. This is one of my fastest learned, most effective puppy training tricks.
I find this command to be one of the easiest to train, yet it amazes me how few dogs seem to know it. I think where many people go wrong is they try to pull the item they want dropped from their dogs mouth. This is the worst thing you can do. You are just playing tug-o-war with your dog now, which every Lab just adores. Start they day you get you puppy, and just practice at first. Teach your puppy to drop it with their toys, and just make it fun. This will really establish the command, then when you need your dog to drop something important, like a shoe or your diamond ring, they will immediately obey because its been ingrained in them. When playing with my puppy, I will grab hold of the toy in their mouth (often a Fleece rope) and without pulling I sternly but calmly say "drop it". I give them about 2 seconds, if they haven't dropped it after that time I now have to show them what I want, I physically open their mouth with my other hand. This is done by wrapping your hand over the top their snout, and putting pressure around their top jaw, focusing on the tip of your fingers which should line up with their top jaw. It does not take much for them to release, and it does not hurt them. I continue to never pull on the rope while my puppy still has a hold of it. As soon as you have a release, you praise like crazy, even if you assisted in the release. Your puppy will learn very quickly what you want when you say "drop It". Your Labrador is very driven to please you, they love a good rewards, weather its verbal or a treat. Play with this command often, consistency is key and it could save your dogs life someday