Lay out a bed or crate for them. Place toys, food and water nearby. Put this in a corner of the room, or against a wall in a reasonably quiet part of the home where the dog is nonetheless "part" of the everyday life.
Take the dog outside to use the bathroom and walk for a bit before they come into your home. Offer ample bathroom opportunites for the dog to go outside on that first day. Due to anxiety, they may have an upset stomach or be unable to control their urination etc.
Clear away black chocolate, avocadoes, grapes, shoes, batteries, remote controls, childeren's toys and precious things from the doggy area. This is just until you know the personality a bit better. Some dogs (like my Boerboel) never touch anything in the house. (He only grabs shoes on occasion to prevent me from leaving the house without him). Other dogs have perhaps never lived in a household setting before, and will need time to learn what is and is not allowed in terms of chewing etc. Set your dog up for success. Don't leave things lying around that they could potentially destroy. If you have a carpet, consider rolling it up incase of accidents in those early days.
Don't give your dog too much attention, especially if they are anxious or fearful. This may overwhelm them. Sit in the room, perhaps on the floor, to avoid appearing overbearing. Read a book or scroll throguh your phone. Allow the dog to approach you in his or her own time. Praise the dog when it approaches you. Ignore any whining or crying; try not to "reward" anxious energy. Try and distract the dog with a toy if he/she touches something they shouldn't. Redirect them onto a "positive behavior" rather than shouting or punishing them wherever possible.
Do not make the mistake of spending every second of the first day with your new furry friend. They will quickly develop seperation anxiety issues. Make sure to repeatedly leave the dog alone, even if its just for a few minutes at a time. Build up to leaving the dog for an hour, two hours, more. Give no attention as you enter or exit the home (or the room). Doing so will just feed into seperation anxiety. I've only ever had this issue with my Rescue dogs, who have abandonment complexes and a deep-rooted fear loosing their Pack. My Catahoula would quite literally vomit when I left the room without him. My Boerboel used to block the door with his body to prevent me from going out. This is a complex issue; I really think it deserves its own post. But for now, just make sure to repeatedly leave the dog alone and return. Give no attention whatsoever as the dog gets hyper/excited upon your return. You want to associate you coming/going with boerdom. I will very camly say "hey Sami" when I come in the door, just to acknowledge his presence. But I will not pet, play or cuddle him until a few minutes after I've come in the door and he has calmed himself down.
Start as you mean to go on! Think carefully about what you actually want. Do you want your dog in your bed every night? If not, then make sure to enforce this from the get-go. Decide what areas of the home you want to designate as "dog free" in advance. Set your boundaries from day one. If you don't want your dog on the couches, just calmly say "Off" and point at the floor on day one. No shouting. Just calm and assertive energy. If your dog doesn't get it, just pick them up and remove them from the couch, or gently shove them down, until they understand "Off".
Do not penalize accidents in the house. Dogs don't understand when you shout at them for going potty indoors. Simply clean up the mess, give the dog zero attention (not even eyecontact) and put them outdoors to do their business.
If your dog barks or howls in the night, ignore it. If you go to your dog, he will quickly learn that you are at his beck and call. He will learn that "barking gets me human attention! Yay!! Lets do this all evening!" Hard as it may be, you have to let them bark until they learn that it is pointless.