first step
Always have your old breadbox ready for battle, connected to a TV, with both Competition Pro joysticks in clear view. Don't lock it away in the basement "in case you feel the urge to unbox it".
second step
Get snacks and drinks and invite your friends.
third step
Wait for the first squeal of joy: "My older brother had one of those! I always had to bribe him if I wanted to play, he wouldn't let me! That's so cool! Does it still work?"
fourth step
Switch it on as if it were as natural as opening your laptop or unlocking your cellphone with a swipe. Let them re-discover the blue beauty of the boot screen and allow them to enjoy the warm memories from 20 years ago.
fifth step
Suggest you could start a little game, "I'm sure you still know this then...."
sixth step
Have tons of fun.
tips
This is not an advertisement, but I am terribly prejudiced towards the 1541UltimateII you see in the cartridge slot. Stuff an SD card full of .d64 disk images from c64.com and enjoy the luxury of a built-in SID Player, ROM emulation (Final Cartridge III it is for me), 99.99% emulation of the C1541 disk drive (including the sound of the R/W head!!!) and much more for ~150,-€ (benchmark: GEOS 2.0 works perfectly!). Of course, you can also try the somewhat less costly variant, the SD2IEC. I have seen it in action once and it also seems to be quite powerful and reliable.
games people play
I usually start with The Great Giana Sisters. Although it never really came out, it was in almost every kid's diskette box, so has high recognition value, is similar enough to Super Mario Land in terms of game physics, and gives a first feeling for the joystick. Also, Chris Hülsbeck's laid-back reggae SID-tunes (and the Level 4 symphony) are as awesome as they were on the first day!
"But don't you have a two-player game?" people will ask after a while. Of course we have!
For a few fast, exciting, simple and highly enjoyable minutes, start Quadtron - based on the principles of the bike race scene in the movie Tron. Surround the enemy pixel with your lines and be careful not to crash into one yourself.
You will only want to play a few rounds of this, because you need enough time for a few more rounds of Burgenkampf (fortress battle). Shoot your enemy's castle to pieces and try to hit his powder kegs to blow it up! Make sure you always keep your own fortress in order, have enough cannon balls and powder and enough money to buy a new cannon or soldier in case you lose yours due to a direct hit. Watch wind speed and direction, set shooting angle and amount of powder and let it rain on the other castle because fvck them for being on the other side of the black mountain! And fvck the mountain too, while we're at it.
A wonderful game of ultimate attrition that, despite being round-based, is highly addictive, will keep you on the edge of the seat and put many an old friendship to the test. The first game is to get a feeling for the prices for repairs (cheapest @ 100), soldiers (cheapest @ 200), cannons (cheapest @ 200), cannon balls (cheapest @30) and powder (cheapest @ 50) (which change randomly from round to round), the second will be a bitter war in your living room over whose turn it is to buy a new flag. For when both flags are gone, you still know the wind speed - but not the direction it is blowing from!
And finally, to stimulate appetite for the next party, throw in an oooold classic: Space Taxi! Pick up your passengers, bring them where they want to go and don't crash your space taxi. Beware of magnets, black holes and moving things on the screen.
And when the afternoon is particularly lazy and rainy and depressing outside, you may even lose yourself in one of the oldest "interactive movies" ever: Maniac Mansion! Man, I dreamed of walking through this house as a kid... I even discovered a new room once.
How do you (re)initiate young and old friends to your 8-bit computer, which games do you load to excite them for blocky pixel graphics and the charm of chiptune music - do you even LOAD "*",8,1 anymore?
Or were you an Atari kid? Ha, you had a ZX Spectrum you soldered yourself with the help of your dad, I knew it. Who needs a GameBoy anyway, right?