How should I select a puppy from a litter?
I've heard different recommendations on how to pick a puppy from a litter to fit a person's needs/lifestyle. I've heard that if I live an active lifestyle, then I should pick the one that runs up to me first, because that one is going to be the friendliest, and easiest to train.
On the other hand, I've also heard not to pick that one, because it will have the most energy, and therefore harder to train. So if I don't live a very active lifestyle, or if I have children, then I should pick the one in the back instead, because it will be the gentlest and calmest.
But, I've heard that the one in the back is also a bad choice, because it's more likely to have problems socializing.
I've always gone by look (a bit shallow I know), but is there really a way you can tell from a litter of puppies how they'll be for the rest of their lives? Is there any truth to these guidelines?
In my experience raising pups, the one that runs up to you is the one that is currently the least tired of the batch. And even young puppies are pack animals, if they are all awake and not particularly tired, they well run at you like a living carpet. I can pretty much guarantee that the one people pick from a litter is disproportionately linked to the one who got the most sleep in the last hour.
@Beo's explanation is best. Be sure to examine the pup in all aspects; eyes, ears, mouth, skin, paws, claws, genitals, etc. You don't need to look for anything specific, just abnormalities.
The size will reflect the parents' size. When choosing the right weight, I always, always ask what weight the parents are. From there you can compare all the puppies size to determine where it's weight will be when full grown. Meaning, if the puppy is heavier than most of the puppies, then its weight will reflect the heavier parent. Watching the puppies eat may also be an indicator as to how big they will grow. If they are eager to eat then they're probably going to be a little more plump.
Temperament has always been my biggest deciding factor. Females are generally more calm, but can also be more 'emotional'. For example, a female is more likely to be in tune with the master's actions and aiming to please, but will take correction more harshly. Males are usually more dominant. There's generally an established "hierarchy" by the time puppies are ready to go home. The alpha is the more aggressive, demanding attention, playful, etc. These can be difficult to raise however (speaking from experience). Being an extremely active individual I always enjoyed the alpha male, but they demand a TON more attention and interaction. After having a black lab alpha I turned away from the alpha after experiencing his overabundant and intelligent disobedience. Anyways, the easiest way to test this is to simply hold the puppy on his back! Flip them over on your lap and see how they like it. Pups that struggle more and resist to submit will be more dominant dogs. (Rule of thumb; rolling over to show their bellies is a submissive position for dogs, if dogs show their belly to you to pet for example, means they are acknowledging your dominance and submitting to you). If the dog accepts that you are holding them on their back, means that they are submissive and more calm.
Personality is my second deciding factor. How do they interact with other pups? Are they playful, far off, aggressive, etc.? Testing this is difficult when they are younger. Make a loud noise (whistle, clap, shout), and observe how they react to it. They more playful, the more 'active' they're going to be.
Play with the parents, how do they interact with you? This is a good indication of how the puppy will be when they are older.
All in all it sounds like you are looking for a dog that is similar to what I picked so here is what I recommend for you:
Don't pick the alpha male. The one that runs up to you and demands attention is usually the alpha male, especially if they are constantly demanding your attention. Alpha's are usually incredibly intelligent. While this helps in training, this usually means they will also intelligently disobey, which is difficult to correct. Instead, look for the second or third puppy to enjoy your attention, but not necessarily rely on your attention.
Pick a male. For multiple reasons: They're cheaper (usually), they're cheaper if you want to neuter them (spaying is more expensive), they're usually more active and ready for adventures.
Test temperament by flipping them over. The alpha will most likely continuously struggle, refusing to submit to you. If you want a dog that is eager to please, don't pick that one. The perfect temperament for me (maybe you), should struggle quite a bit, but eventually they will let you hold them in such a way.
Lastly, any dog can be a great dog, it simply depends on how you train it. Love you animal and be consistent! Best of luck and cheers.
Experience: I watched Marley and Me and a Cesar Millan youtube video once. JK, seeing eye dog trainer, but just recently settled down to purchase a pup for my family.