I hold meets for those new to pinball over here in Australia regularly primarily for those who have either purchased a machine from me or know someone who is in the market for one.
The best meets for newbies are those that are kept simple with a relaxed atmosphere with no outside rigmarole or hoops to jump through.
Have a competition of sorts on the night but don't bother getting it sanctioned externally - it just complicates matters and you lose most of your autonomy on what is at the end of the day your private property and chattels.
Just a straightforward inhouse competition using one of the simpler formats suggested above.
If you want to make it challenging then offer prize money by charging a door entry and distribute it accordingly at the end of the night.
Stump up for food/catering out of your own pocket as an act of goodwill. Attendees will appreciate it more and positive word of mouth spreads.
Try and keep the alcohol as BYO minimal or discourage it. A lot of my meets are family freindly and it isn't out of place to see wives and kids attend without the environment that excessive alcohol consumption tends to bring. On that note have at least a couple of redemption machines on hand stocked with toys on freeplay for the kids who will inevitably get bored with the pins.