I'm an aspiring house doctor and about to embark on a project to maximise the selling price of a property my family have inherited.
Things I will be focussing on are all quite obvious, so you may already have thought of them, but just in case anything here is helpful...:
Kerb appeal, tidy, now, paint, plant front garden and drive area so that drive-by viewers will want to have a look inside.
Making sure the walls and floors are light and neutral. You may love a bold feature wall but it can be off putting. This isn't your home anymore - you need to let it go so that you can move on, so start detaching from it by changing the decor.
New carpets if needed. (I appreciate for a quick sale you might not want to spend time and money but this may be an investment worth making if it hurries things along)
Making sure it smells fresh (no smoking, pets, overbearing air fresheners etc) while on the market - even if you think your house doesn't smell, to someone else it might do. Put cat litter trays outside and perhaps try to send dogs next door for half an hour during viewings etc
Clearing the majority of personal possessions. People want to imagine themselves living there, so while your collection still and photos make it feel homely to you, they do the opposite for a buyer. Start your packing early and get things out of the house. Even if you fill the garage with boxes ready to go, the house will be clearer.
Using rooms for their intended purpose. Some people are stupid. If you don't put a bed in a bedroom they won't be able to imagine it with a bed in it! Obviously most of us can see past these things, but if your viewers are some of those who can't then you're stuck.
Freshen up kitchen with new worktops or tiles if needed to modernise it. Don't spend a lot unless you're prepared to completely gut and replace, as it may not be to everyone's taste anyway, but it's one place (along with bathrooms) that needs to be clean and clutter free.
Does your agent know about local schools and amenities? Important to be able to sell it properly.
These seem to be the staples of most property programmes I watch, so I'm sure you'll have already thought about most of these, but if not hopefully some of them might help?
3 viewings in 3 weeks is pretty good so don't get down heartened.