Right the main problems we have in Labradors are hips, elbows and eyes. They tend to be nice natured, biddable dogs. I could live with a lab.
It is vital that when you look at buying a puppy both mum and dad have had their hips and elbows scored. It's like golf and the lower the score the better. They publish an average for the breed (breed mean score, BMS) and both parents should be below that to be used for breeding (lower the better). They should also have had their eyes scored, there are 2 methods of doing this. The first is by examination by a certified vet who specialises in ophthalmology - they look in the eyes and if they are normal give a certificate that is valid for 1 year. The better method involved a DNA blood test that detects whether the dog is carrying a bad gene predisposing it to eye problems.
When you go to buy a puppy make sure that you visit it at the breeders home and see the entire litter and the *****. Accept no excuses even that all the others are sold. You want to make sure they are reputable and the mother has nice temperament. When picking the puppy make sure that you get a forward going one and not the one the cowers at the back. The cowering puppy can turn into a nervous snappy adult.
Once you have the puppy home you need to feed it on a good quality puppy food, it is worth spending some more money on a good quality food at this stage. No need for milk or strange diets advocated by some breeders. If you need to change brand of puppy food from the one the breeder uses do it gradually.
Our practice policy is to vaccinate puppies at 9 and 12 weeks, they can go out and socialise 1-2 weeks after the second injection. Before they have completed the course they shouldn't go places where they can meet un-vaccinated dogs and should be carried in public. It is good for the dog to meet and socialise with friends dogs who are vaccinated as it can be a lonely time for a new puppy. Prices vary but first vaccination is likely to be around