Homeshare host here. Prior to my first guests, I did a deep clean of the room and bathroom, bought new towels and bedding, repurposed an old sofa table, bought a tiny flat screen TV for the room, and in general made sure everything in the room and bathroom was focused on the guest.
The most important thing I did prior to my first guest, in my opinion, was switch out my plain deadbolt to add a keypad lock on the door with programmable codes for each guest. This has made hosting so easy!
As a guest myself, I'm amazed at the places I've stayed where it feels like I'm just staying in the "spare room." Christmas decorations in the closet, personal items stored under the bed. It just feels weird! I always want my guests to feel like this is "their" space while they are here.
I find I am constantly adding new touches. I've now got three sets of towels, two sets of linens, and two bedspreads. I've added several pieces of artwork. The bathroom cabinet now holds a full supply of toiletries and first aid supplies. I've added a curtain in the doorway to the tiny hall of the guest bedroom and bathroom to make it feel more private.
And most recently, I removed the bifold closet doors to make the room look more open. Guests don't need closet doors and it allows for extra space to put another little table with shelves! Next up is a plan to upgrade my double bed and VERY old mattress to a queen bed and memory foam mattress by the end of the year.