Get some sick artwork done
If you know a graphic designer or artist, hit them up and see if they want to work with you on some party artwork. If you don't, find a local artist you admire online and send them a nice email. A little cash helps in both instances too.
If you're into throwing a proper club night that enjoys a nice lifespan and earns a bit of a rep, you're going to have to enter the game with strong artistic vision. If you're throwing a party for a laugh or for an occasion, whip something funny up – this is where basic photoshop skills and access to vintage Facebook photos come in handy.
Find a venue that people will feel comfortable in
Your club night needs a nice-sized dancefloor, reasonably priced bar and a capable soundsystem. Make sure the owners are good people that you want to do business with (sounds corporate but, at this stage, it pretty much is business) and double-check that all the equipment in your venue of choice is of industry standard. Go for a place that fits your vision and that your mates feel comfortable in. Want it scuzzy and dark? Get a basement. Want a little bit of class? Approach an established club that helps bring up new talent. And don't go for anything too big, either. You don't want your rave to feel totally empty if things go wrong.
If you're really ambitious, try finding a venue off the beaten track and make it your home. Or blag a warehouse or DIY space so you can wheel in your own soundsystem and all your friends can bring their own booze.
Ask your friends and friends-of-friends to play
We're betting you know a ton of DJs. Get them on. Ask your closest allies as well as heads from other social groups. The more crews you bring together, the more people will turn up. A good party must also be a strong community hub: it's all about friends coming together and raving together. So round up your squad but reach out as well. You never know, you might send up with some new BFFs after your party goes down in history among everyone involved.