Where should I start Star Trek, based on my interests?
So I always enjoy some good sci-fi like Doctor Who, and much prefer sci-fi that is focused on creative concepts/hypothetical situations (like Dr Who) rather than futuristic action (like the most recent Star Trek movies). I've been told many times that I'd really like the older Star Trek shows given that, especially since I am really passionate about space travel and am heading into a career based on it. A few months ago I stumbled upon some Star Trek on tv and watched the episode about a tiny light-like life form that is brought aboard the ship and begins to become intelligent and communicate, and an episode about a planet run by women (forgive me for not knowing the names or what series it was, I'm a total noob at ST). Absolutely loved them.
So now I really want to get into watching the show thoroughly. Problem is I'm an engineering student who won't have much time, and I know there is a lot of Star Trek out there to watch lol. So I was wondering if any of you could recommend a good starting point for me, a series that matches my interests but doesn't require a huge amount of knowledge about the ST universe. Assuming I continue to enjoy it, I'll definitely get around to watching it all one day, but for now I just need a solid starting point.