Re: How to begin?
I would say, pick the ten best episodes of TOS by fan consensus and watch them. Then watch a lot of TNG and DS9. If that doesn't make you a Trek fan nothing will.
Why? Why should someone bypass TOS for TNG/DS9 when they were seemingly drawn in by the big-screen action-adventures of Kirk and Spock. That would be like me telling someone who liked First Contact
and an episode or two of TNG to go watch TOS instead.
"When I first heard about it (the Enterprise underwater), my inner Trekkie was in a rage. When I saw it, my inner kid beat up my inner Trekkie and made him go sit in the corner." - Bill Jasper