If you're regularly throwing parties or hosting events that lots of people attend and seem to enjoy, then you might not need to read this post. If you're new to throwing parties, or just want a checklist, this might be for you.
Also, keep in mind that nearly all the advice here depends a lot on your social environment. If the kinds of people you want to invite to parties differ meaningfully from the kinds of people I typically invite to parties, you need to take that into account when deciding how to interpret a piece of advice.
Consider whether you want your party to have a theme, specific vibe, or be focused on a structured activity. More opinionated parties can be more fun, but usually impose a stronger filter on who's going to want to attend. If you aren't sure whether a theme/vibe/activity is going to be appealing to enough people to make throwing a party at all worth it, consider asking someone in your social scene with more experience throwing (or attending) parties.
Your party probably doesn't need to be that opinionated for people to have a good time, if you're inviting the right people.
If your party is going to be opinionated, that might influence many of the other considerations listed below.
Weekends are traditional. If the party is going to in the evening, Fridays and Saturdays are better than Sundays, because people don't have work the next day. Many people find that the cozy late-night conversations that happen once the party has passed its peak attendance are disproportionately fun compared to the rest of their experience at the party, so scheduling parties in a way that allows for that can be good.
On the other hand, this means that other weeknights will have less competition, which can be relevant if you're part of a highly active social scene where a lot of people are hosting events and people often end up having to choose between different events happening at the same time.
I've found "about two to three weeks in advance" to be the best time to send out invitations. It's far enough in advance that people will often still have their calendar open, but not so far in advance that people feel disoriented or reluctant to commit to something that far in advance. The "ideal" lead time is one of those things that might change dramatically depend on your social environment. (One example consideration: are you inviting parents of young children, who might need to make arrangements for child care? Such arrangements can be stressful and difficult to line up on very short notice.)
If the time of day you're hosting the party overlaps a common meal time (usually dinner, but sometimes lunch), you should either be prepared to feed your guests, or expect many of them to arrive somewhat later, after they've eaten. Either way, you should explicitly communicate what the food/snack/drink situation will be at the party.
Consider how many people you ideally want at your party. Then try to figure out how many people you need to invite to make that happen (while not drastically overshooting your venue's capacity). This ratio depends enormously on various contingent details, but you can at least try asking other successful party hosts you know what their typical ratios are, and then assume your ratio of "RSVP'd yes or maybe" to "actually attends" will be slightly lower than theirs.
You can sometimes increase turnout by sending out personal invitations rather than via a platform, though doing this unjudiciously might annoy people. Use your best judgment about how well you know the preferences of the people you're inviting. You could try asking them how they prefer to receive invites, but many people will find being put on the spot like that uncomfortable, as it might require them to tell you that they'd prefer you not message them directly for party invites (or else lie).
This one is kinda hard to give fully-general advice on. If there's food (or snacks), but it isn't an explicit focus of the party itself (i.e. it's not a dinner party), get disposable plates, bowls, cutlery, and cups. One per person is not enough. People will routinely go through multiple plates/cups/etc, because carrying them around is annoying. Running out is extremely annoying. Don't be afraid to overdo it, the cost is trivial compared to everything else, and if you're regularly throwing parties they won't sit unused in a cabinet somewhere for long. Also, make sure you have enough trash cans (or at least trash bags) scattered throughout.
Consider whether your likely attendees have any dietary restrictions. You don't have to satisfy them, but it's good to understand them, so that you can communicate whether the food you'll be providing will meet them or not.
This one is also pretty hard to give general advice about, and depends even more heavily on your social circles. I mostly don't drink anymore, even at parties, but that's substantially because the costs (to me) have gone up, not because there weren't any benefits. It's important to understand what kind of party you're trying to have, and who you're inviting, when deciding whether or not to have alcohol at a party (and if so, what kind). There are some people who reliably cause other people to have a bad time when inebriated. If inviting those people to your party is important to you, consider options like:
Remember that red wine stains pretty badly, if you have carpets/upholstery/etc that you care about.
tlevin suggests that music serves the role of reducing average conversation size (usually a desirable direction to push in; having ten people in a circle where one or two people are doing most of the talking is a common antipattern). I, personally, am not convinced that music is the best way to accomplish this goal, though it might help if rearranging your space to make it impractical for large clumps like that form is difficult or costly. This is one of those things that has a bunch of trade-offs and whether having any music (and what kind of music, if so) is good or not depends on the vibe you're going for and who you're inviting. If you're inviting a bunch of people with auditory processing issues, consider not having music. Playing music can also interfere with e.g. song circles or spontaneous jams, if those are the kinds of things that seem like they might happen at your party.
If you're in a geographic region where the availability of transport and/or parking is uneven and people might have expectations that could be violated, include the "obvious" details in your invitation/party description.
You can often rope the last stragglers at your party into helping you clean up without too much effort, if they're a pro-social bunch and you actually have useful things for them to do.
Figure out how much time you'll need to clean up both before the party and after the party, and schedule your party accordingly.
In my social circles, Partiful has supplanted Facebook events as the default platform for organizing events. Some people also use Luma (more frequently for paid events). Many people find the fact that Partiful uses SMS as the default notifications channel pretty annoying; keep in mind that you can configure how often and when your attendees get reminders about the upcoming party (among many other configurable settings). I think it's basically a fine platform.