As others have said, make sure your house is generally clean and non smelly and their room in particular is tidy and nice. If you have pets pay particular attention to the smell and hairiness of the rooms they use, as pet owners we tend to go 'nose-blind' to the lingering odour of our darlings 
but we forget not everyone is as keen and the smell or hair can bother others in particular if they have any allergies, when he last came over my brother kindly informed me my house has 'eau de guinea pig' lingering around it which I can't smell at all 
so I will be scrubbing out their hutch and thoroughly airing the room they are in before any future guests come for sure! Otherwise I wouldn't panic re doing too much cleaning, obviously you want the place hygienic etc but personally I would rather there be a bit of mess and a relaxed/happy host than show home perfection but host a frazzled mess!
On the topic of pets do have a plan to separate/restrain any particularly exuberant or noisy animals (or indeed, children!) from your guests who may not be as keen on them as you are!
Food, I always go a bit OTT for guests personally but I would say get in their preferred drinks both hot/cold, soft and alcoholic (if you don't know what they like then I guess a selection of tea/coffee/herbals/juice/pop/wine/beer), some nice snacks and then a range of breakfast items unless you plan to go out for breakfast. Cold breakfast is fine, I wouldn't necessarily do a cooked breakfast except for certain older relatives I know like them, although it is nice to get those part-cooked croissants/pain au chocolats from the supermarket that you can pop in oven for 15 mins. For lunches/dinners you can discuss with your guests and fit around your planned itinerary, you shouldn't necessarily have to do all the catering although on a weekend visit I usually do at least one hot home cooked meal and maybe a buffet or cold lunch or two, and then we'll eat out or get takeaway for other meals (guests will usually offer to pay, I'll gracefully decline, they will insist and I'll let them pay at least once 
).
I think the key to a good visit is to keep busy, even with my nearest and dearest sitting around the house chatting gets boring after a while. What/how much I plan depends very much on who's coming, my mother for instance is pretty much incapable of independent thought and when asked what she'd like to do just says 'whatever you like' so for her I'd very much plan an itinerary (garden centre Saturday AM, lunch at pub, shops Saturday PM and so on) whereas with other friends we can be more spontaneous but I'd still have a few ideas ready just in case e.g. we could go to local nature reserve or the cinema is showing X film or we could visit Y local attraction (good to have wet weather and dry weather options also!), so maybe a bit of googling of what's on esp if it's things you'd need to book? Also on a longer visit you may want to discreetly find/hint at things your visitor can do without you in tow/ways to have some individual time or time with other people, being in each others company 24/7 for prolonged periods can be a recipe for disaster IME!