Ok, if you are happy to take the puppy then you need to be prepared. Firstly I would definitely crate train. I had never used a crate until I got the dog I have now at 9 weeks. I live in a house that is impossible to make totally safe for a puppy so a crate was the safest option. He loves his crate and still sleeps in it all the time (he is 5 now). I had intended getting rid of it when he was 1 as it takes up a lot of room.
You need to think about where pup will sleep for the first week or so. He or she will likely cry for the first couple of nights as they are in a strange place and missing their mum and siblings. Me and DH did not want our pup in our bedroom so we took it in turns to sleep downstairs on the settee. We started with the crate next to the settee and when pup woke and cried we talked softly to him and stroked him through the bars. Most times he went back to sleep. If he didn't we took him in the garden assuming he needed to toilet.
A young pup needs about 5 meals a day. We fed things like porridge, scrambled egg for 1 of his meals. We also gave him goats milk - dogs should not have cows milk. After they have eating go outside in the garden with them and when they pee or poo give loads and loads of praise - "Oh good girl/boy" etc. If you see them start to toilet indoors pick them up and take them outside and again loads of praise as they do it outside. Don't ever tell them off for going inside. I personally do not recommend using puppy pads or newspaper as it teaches the pup to go inside and you have double the amount of training. You may be lucky and have a dog that learns quickly. My dog was clean within a week but I have had previous dogs that have taken much longer (the worst was one that took almost 6 months to be totally clean indoors). It is frustrating if they are slow learners but they will get there
Start teaching commands like sit, stay etc early on. Have short teaching bursts and, again, lots of praise. Never be negative even if it seems they are not getting it. Very young dogs tends to picks things up quickly though. My dog learnt to sit in about 2 hours and he is a breed that is supposedly thick!
I would buy a harness. I find them easy to use when walking. They are far more difficult for a dog to wriggle out of than an ordinary collar plus if a dog pulls when walking and puppies often do it can cause damage to their throat.
I practiced lead walking indoors and in the garden before I took my dog out in the street although for the first couple of weeks he spent most of his walks with all legs in the air! He jumped around at excitement at everything - leaves, people, other dogs, cats etc.
They will probably want to be with you all the time and follow you round, even to the bathroom if you let them. Personally I allowed this but I did also get pup used to being on his own but very slowly. I would put him in his crate, go out the front door and just stand and listen. I literally started by going out for 1 minute and building up on time.
If you have a car get them used to car journeys as soon as possible to lessen the chance of car sickness. Again build up journeys slowly if possible.
Be warned, puppies can be very hard work and take up almost all your time. You will probably have disturbed nights too. I have been told it is similar to having a baby but as I am childfree I don't know if that's true.