Got Walter Koenig's signature during a book signing for Checkov's Enterprise early 1980 at local mall Waldenbooks. Played hookey (called in sick) from gradeschool to ride my bike a significant distance in freezing rain Michigan March weather to attend. Free to attend and talk for hours ,shake hands, have him sign other stuff, etc. Just had to buy the paperback
I was alone with him for what seemed like hours- it was the middle of a workday/week in the Midwest so sparse attendance, a local Trek club geek "president" arrived to interview him after a time.
Jame Doohan 1986- appearance at local Highland Appliance store (Best Buy/Circuit City of the 40's-80's around Michigan)
Free to attend and bring whatever you wanted signed. Significant attendance since it was well advertised and between ST3 and ST4. I brought my 70's edition Franz Joseph Starfleet Technical Manual
and he signed the Enterprise 1701 (no bloody A, B, C or D!) schematic page, plus a photo plaque I brought of the TOS crew on the original bridge, plus he gave away 8x10 headshot Scotty glossies he signed per your instruction! Shook his hand and discovered he was missing a finger at that time from WW2 D Day. 3 signatures from Scotty in one fell swoop! All free. Assume he was paid by Highland Appliance to show up.
Marina Sirtis and Michael Dorn ~1996 Dearborn MI Trek convention. Marina came through the same entrance all the fans/attendees did and interacted with the crowds, complimenting fans for cosplay, visiting vendors, yelling into the crowds to have fun, etc. No problems having items signed, hugging, etc.
George Takei ~1998 Borders Books appearance. Just show up and wait in line. I brought some Captain Sulu audio books on CD I already had (i.e. didn't have to buy anything)
which he signed graciously (label side of discs), shook his hand, small talk. Nice guy, no pretentiousness whatsoever, comfortable with fans.
Those were good Trek memories...