For me the main thing is to get people pumped from the first invite.

Like don’t write: ‘hey I am doing this thing for my bday on Friday, wanna come?’

But come up with something like: ´Ok people, I just read in a recent Nasa report that the planets are going to be lined up on Friday evening. Coincidentally, this is the day I am turning X. So, I was thinking it would be the perfect opprtunity for us to show the entire solar system how it is we do it on Earth.’ then some fun lines about how we’ll make Marsians green, and have more love than Venus, and what not. stupid puns like ‘don’t sit on Uranus and come party like you’re the sun’ tend to work nicely.

You get the idea. Be totally over the top in your invites.