We decorated the space for our family's needs and tastes because we use it part time. We call our place "mother-in-law" approved. A number of people wrote in our guest book that it felt like being in a home instead of a rental space. Here's some tips:
1. Decorate to please yourself. I have booked sterile (but attractive) Airbnb's and they don't feel comfortable. Just feels like a Residence Inn or an Embassy Suites. I much prefer the ones that feel like you can sink into a couch and be "at home" temporarily.
2.Don't scrimp on high quality items. They hold up better to abuse and use than low budget stuff. If it's particle board or MDF - you'll eventually be sorry. They break easily and are susceptible to moisture. Go for high quality fabrics and hardwood furniture frames when possible.
3. My secret weapon? Estate Sales from upper income homes/neighborhoods. Shop the ads and look at the photos. If you see something that fits your needs and it's in your budget buy on first day. Designers will be competing to get the best things for their clients. If not, see what is left on the last day of the sale (half-price day). Be first in line (In the U.S. you can put a marker down then go sit in your car). If the house is packed sometimes things are marked down 75% on the last day since the remains will be sold for pennies on the dollar to liquidators. Do not forget to poke around in the garage or basement for odds and ends you didn't know you needed until you saw it. Many times you can find things with the tags still on them.
4. Decorate - Put pictures on the wall. Or mirrors. Or clocks. Those things make it feel like a home.
5. Use IKEA or other stores for things that are less important (plates and silverware, for example). Although we found bone china by Mikasa at Costco on clearance for less than IKEA was charging for plastic dishes. We found a full set of Corelle dishes and bowls at a thrift store for $5 total.
6. IKEA has reasonably priced curtains. Use white sheers beneath them - they'll cast brighter light into a room.
7. Keep tinkering. As you find better things, donate what you have been using and trade up.
8. Sheets and towels from Costco have lasted for a long time. When they go on sale we buy multiple back-up sets and put the extras away in case of accidents on existing inventory. We keep an iron and an ironing board on site because iron the pillow cases to look more crisp after they come out of the dryer. (we hang them in the closet for the next time they are needed.)
9. Games, books, DVD's are helpful. We took over games we liked to play but were not attached to (in case pieces were lost) and supplemented with others we found when thrifting. A number of families left notes about being able to play board games at the dining room table.
10. Whiteboard you can use to greet guests. We write the names and a welcome on the board. Sometimes people erase it and leave us a note of thanks when they check out.
11. Put a patterned rug inside the door to catch muddy boots and shoes.
12. Put security cameras on your front and back door. You'll thank me later.
@Huma0 , I use battery operated sensor lights as I don’t like the idea of running electricity. Mine use 4 x AAA batteries. (NEveR anything with button batteries for safety) Mine are on shelves, little side tables etc, so they can be flipped if not needed. But the particular ones I got can be stuck via adhesive two sided tape or little screws. I got mine through promotions at Bunnings ages ago. But there are many types out there. 💐
Totally agree with @Christine615 & @Lawrene0 , my friends.
We also use the space for ourselves and family and friends, so it has to feel like us…
I buy tea towels, bed linen and towels that I’d happily use. I leave items for use that I would want, including food condiments, what we supply upfront and board games, books etc.
After all, it is our downstairs space, that just happens to gets used by AIrbnb guests, between our use.
So with taking on some painting of late, (on the easel) I may even upgrade some art work in the space. But that will have to wait till I can visit a framer.
The wonderful tutoring artist who has graciously taken me on as a student in her online workshops, just happens to be my cousin, so for the last seven months, I’m in brilliantly talented and safe hands…. 
