When I see a post like this, I can't help but think back to when I was first getting into the hobby and the amount of stuff I knew I didn't know much about, but even worse, the stuff I didn't even know I didn't know. I was maybe a year or two in before I discovered Cloudy Nights and some other forums, and wow, did my knowledge level increase exponentially after that. It still takes doing, actually getting out there in the dark with equipment experimenting with techniques and processes, not just arm-chairing it... but the research potential on CN helped save me from making some... less than ideal decisions that a typical beginner is tempted to make. In my case, I had already made those poor decisions. And to some degree, those poor choices really hindered my progression for the first several years in the hobby, especially as I ended up trying to make a challenging set-up work but without really having the requisite skills or knowledge to make that happen. I can't say those first two years were a total waste, as I definitely learned a lot. But I really became disillusioned with the hobby until I pulled the trigger and completely rebuilt my gear kit new, with better goals in mind.
So, if I could tell my younger self what to do, what would I say?
First, never stop researching! CloudyNights.com is great for, go figure, cloudy nights. Read a ton, look at lots of pictures here and on astrobin, get a feel for what you might like to try and what is likely less important to you. Read up on the differences in DSO imaging, planetary imaging, and galaxy imaging, and the different pieces of kit they need. Find a local club, talk to folks there, see their gear in person.
Second, to parrot what everyone else already said, get a decent mount that you can grow into early. All the ones that have been mentioned would do you well for several years while you build your knowledge and skills in whichever form of astronomy most appeals to you, and if you start with a quality mount from day one, you really only need to upgrade when you decide to increase your telescope size/mass.
Third, and here is where I likely diverge a bit from some other recommendations, is to just get some relatively cheap telescope, a couple eyepieces, and maybe research what you'd need to hook up a Canon or Nikon DSLR camera (assuming you already have one), and just get outside and use that gear for a bit. Spend time learning the mount, get good at polar aligning it, do a ton of Go-Tos and see what's out there, get used to setting up the gear and breaking it back down. The scope and the camera almost don't matter at all here (although I'd probably get a scope in line with your goals in the hobby, so maybe a 60-80 mm refractor if you're leaning DSO imaging, or a small SCT or Newtonian if you're leaning more planetary/galaxy), the point is more to get familiar with the basics of telescopes and mounts. Any photography you do at this point will be mostly just to get used to acquiring the data and learning about the basics of processing, which even with just a DSLR will be a mountain of new information and skills that will take you time to get accustomed to. If you want to do some Electronic Assisted Astronomy, which let's you see more at the scope than what you can normally see through just an eyepiece, adding on an ASIair will let you control your camera and build what's called a "live stack", which is also great for sharing with the family in the moment. But really, this whole step is all about getting acquainted with the fundamentals more than anything else, and just enjoying being under the night sky at your rig. I cannot overstate how cool a feeling it is when the basic fundamentals start coming together and it all just makes sense what you're doing and why it works the way it does. (But I'm an applied sciences nerd at heart, and the technical challenge of astrophotography is what really got me hooked in the first place, so YMMV. But I still recall seeing my first stack of DSLR raws come out of Nebulosity... that stacked frame, and the resultant postprocessing I absolutely hammered it with, was truly atrocious! But it was MY data acquired on MY gear that made that frame, and that was just the coolest thing... I had captured that gentle rain of photons from a faint-fuzzy that I couldn't even spot with my naked eye, and made something of a pretty picture of it!)
If I had to do it all over, I'd probably advise myself to stick with just these for the first 3-6 months. In my case, I totally failed on step 2 and had a horrendous time trying to make astrophotography work regardless of the money I tried to throw at the problem, and even to a degree on step 3, because when I corrected my issues with step 2 I still focused more on the scope than the mount, and ended up with a system that worked... but just barely and with unnecessary complexity that made things harder (and more costly, ultimately) on myself.
At any rate, when you are ready to up your game, you'll be in a position to leverage your experience on a good mount which you can just keep on using. I would just go incrementally wherever possible. Maybe first add in tracking for the mount. Then maybe switch from a DSLR to a dedicated astro camera. If you hadn't yet added an ASIair or something like it to your rig, now might be a good time for that as well. And so on.
Final bit of advice: Never be afraid to ask questions! There is a TON of new knowledge coming your way, and a lot of it is non-intuitive. It's beyond easy to get confused and overwhelmed, and if you're feeling lost, you probably aren't having a great time with the hobby. And if you aren't having fun, you probably aren't getting out to the scope, and the only scope worse than no scope is the scope you're too dejected to use. So, fire away! This is a great community here, and chances are, someone will have been in your shoes and can offer good, logical suggestions.
