I start whit the old Enterprise, the first episode is a bit whyrd as there is no Kirk in and the Crew is also different, (expect Spock) , then I want to watch the first Kirk Episode, and then Enterprise and TGN Simultaneously.. like someone meantioned on the German Nintendo Boards..
Whit best regards, Matthias
If you want to watch them in chronological order start with Enterprise, then Discovery, then the original series. That might help you understand where Pike and friends fit in, and give you a bit of back story on some things (the look of the Klingons, for example).
Technically it all starts with the movie First Contact. If you really wanna be picky there are individual time travel episodes in each series that predate that, all the way back to the 19th century if I remember correctly. Really, though, those are best as a part of the series they belong to, with nods to others sometimes (DS9 visiting Kirk).
When you get to the last few seasons of TNG they lead into the events that are precursors to DS9, and for a couple seasons they take place at the same time and have crossover scenes (Quark and Bashir show up on TNG).
Same for DS9 giving info about Voyager, which is a ragtag crew (they aren't all Starfleet).
If you want to watch it the way many people our age did start with TNG (BEWARE: the first season or two have a very cheesy TOS feel and stories, but you need some of those later, especially a couple of the Q episodes). You can start watching DS9 where appropriate which makes it feel like TNG is a little bit longer since you are watching both at the same time. Regardless of how you do it I recommend watching the movies in the correct order (except as mentioned earlier) and don't watch Generations until you finish TNG. I know myself and others around my age didn't watch TOS until after TNG, so it will all make sense if you start there.
I could talk all day about all things Trek related, so lemme know if you have questions. I watch it almost every day, so...