When my mom threw her first party after getting married, she decided that the curtains needed to be washed. So she took them all down the morning of the party and tried to wash and iron them before the guests arrived. Obviously that worked about as well as could be expected, and the day that I was throwing MY first party after getting married, my mom cautioned me to not make the same mistake she did. (Little did she know that I had the same curtains up for four years and never washed them once before replacing them, but we'll just hope she didn't read this part.)
So let's talk about how to get ready for a party with as little stress as possible! Here are some things your guests absolutely care about and want to see at your party, and what they truly will not notice:
Your guests want delicious things to munch on and drink because everyone likes delicious things, but also it gives them something to do when they've managed to get into an awkward group of people they don't know very well. "Just gonna go grab some more crab dip, excuse me!" is a perfect way to exit a conversation. We've all done it.
What they won't care about? How much of the food you serve is handmade and how much of it is purchased. Also, as much as they may be delighted by a perfect Pinterst-y spread of theme-appropriate snacks, they will NOT be disappointed if there aren't any. Is it food? Does it taste good? You've already won them over.
Try coming up with a menu that can be prepared mostly ahead of time. Some things will always have to be made day-of, but give yourself a good mix of items that can be made the night before (any kind of dip is actually better if it's had time to chill out in the fridge; same with any kind of punch) and a couple that can be made early in the day and just warmed up if necessary, and some purchased snacks that just need to be arranged (like cheese and crackers or a box of cookies from the bakery).
Also! If you tell people not to bring anything, be prepared for someone to not care what you say and bring something anyway! If you're arranging a table for the food, make sure it's not so packed in that you'll have to throw your guest's contribution on a side table and make them feel bad. (I mean, maybe their contribution stinks. But you still invited them to your party, so you should try to make them feel good. Even if the food they brought stinks. But don't tell them.)
Do you have enough seating for the amount of people you've invited? If there's a weird parking sitch at your place, did you let people know ahead of time? Are you having a viewing party for a sporting event, but all you have is a love seat in front of a small tv? If you have a small space to host your party, make sure you invite the amount of people that can comfortably fit there. No one wants to be squeezed into your studio apartment party like a bunch of people desperately trying to get to the bar before their free drink tickets expire. Make sure that you have inviting and comfy spots to sit. If you're serving food but asking people to sit with plates on their laps, don't serve anything that needs to be cut with a knife. Have enough cups and plates and napkins so people don't have to improvise or poke through your cabinets to find something else they can use. If you're playing music, turn it on before the party so you can find a good volume compromise between "why are we even playing music when I can't hear it?" and "WHAT? WHAT??? I CAN'T HEAR... WHAT????"
Also, find an easily accessible space for coats and bags. A coat closet with a good amount of hangers is great, but if that's not an option, a bedroom or office space where these things can be placed is fine, as long as you let your guests go in and out on their own. Being a good host and taking someone's coat for them is a lovely move, but what happens when they want to pop in and grab something out of their purse and they have to ask you to get it for them? Because they probably need Pepto Bismol because they ate that stinky 7-Layer dip that your friend brought and they don't want to tell you that they need Pepto but they know you'll think asking for their bag means they're leaving and when they say no you'll ask what they need their bag for, when really they just want to discreetly take something so they can stop hopefully-discreetly-but-possibly-overtly-oh-god-how-many-people-noticed using the bathroom and you're making it really difficult for them by being the gatekeeper to the coat room right now. So just let your guests go in and out at their leisure and then gossip about them when they go home. (Don't really gossip about your guests. That's not nice. But I know you'll do it anyway. So just make sure they've all left before you start.)
A RELATIVELY clean space.
You know what's gross? A toilet that hasn't been cleaned in two months. Dog hair in every ice cube. A giant pile of dishes on the counter. You know what's not gross? A little bit of dust on your bookshelf. Some dishes piled in the sink. A slightly wrinkled curtain. Your guests want to feel welcomed and invited and part of feeling welcomed is feeling like you're walking into a space in which the inhabitants have taken some pride. But if you forgot to vacuum up the little specks on your carpet, or take the hair out of the drain in your shower where no guests will be going (and if they are - don't invite them again! Or at the very least, tell them, "Hey Larry! Stay the hell out of my shower while you're making a brief appearance at my cocktail party, you weirdo!"), don't sweat it! No one is noticing this stuff, except for your nosy neighbor or your great aunt who was turning up her nose at all of your guests' clothing choices, so who cares about their opinions?
The day before the party is a great time to give the bathroom a good once-over, vacuum or sweep up, and put away any junk in spaces where your guests will be (put that junk in any space your guest WON'T BE: pro tip). And the day of, give your kitchen a quick clean (get as many dishes done and put away as you can spare, and wipe down your countertops), and go get dressed for your party knowing that you didn't get yourself monstrously sweaty because you were spending all day cleaning the shed in your backyard just in case someone wanted to creep in there and you know you'd be mortified if they saw your haphazard jumble of yard tools.
So, have some good food, a good selection of drinks, a good amount of chairs, and a good-enough philosophy on how clean your house is, and your party will be well-liked by your guests, and relatively stress-free for you! (I mean, it won't. You're always stressed. Everyone is always stressed. But hopefully you won't be sweaty!)