The main aim is to get as many people through the door as possible, so make sure you're bumping up your adverts on your various advertising portals.
Viewings & dressings
Viewings - book your viewings strategically, show them all available rooms. Sometimes tenants will tell you they have one budget, but then miraculously find more money when they see a bigger/better room. That being said, if you have a smaller room in your HMO that's struggling to rent but also have a slightly bigger & nicer room to let in the same house, if you've showed them the smaller room and they seem to like it - don't show them anything else (the bigger room will always let out faster). Make a good impression as viewers have friends who will spread the word!
Rents - Always try to achieve higher rents! Don’t be unrealistic, but have a look on the market and see what other rooms are going for and how your rooms compare. Tenants will pay for quality. If your property it done to a higher standard, you can push for more rent.
Dressings - As with professional photography, you only have a small window to advertise. Dressing a property will not only make it stand out from the rest on the websites, but when you take tenants round there for viewings, it looks more homely and they can visualise how all of their belongings will look and also get a better idea of size.