Turntable newbie info site?

I am feeling much more comfortable starting my TT experience with the Technics SL1200G and see that there is a very lightly used one for sale on the forum.  Getting close to purchasing it.  If I do, I will ask for advice on an initial "starter" cartridge.  Thanks again for all of the advice given.  I believe it has saved me time and money.

The best way to save money is to spend time. So you are off to a good start. Go and listen to as many rigs as you can. Getting good LP playback everything matters. So pay attention to every detail in the chain of everything you try- table, arm, cartridge, what the table is sitting on, phono stage, all the wire, and of course also the system its being played on.

Best is if you can find a place that will let you play the same record on the same system with different turntables. Good luck. But try. 

Another thing, relax. Every turntable out there is gonna do very naturally what every CD ever made never has been able to do: make music. I'm not kidding. I dug out my old Technics SL-1700 (with an old Stanton 681EEE with a bent cantilever) and my wife and I both preferred it to CD. Analog also tends to retain its value a lot better than digital. That same old Technics SL1700 from 1976 is worth more today than it sold for new. Digital? Disposable. Deservedly so.

So relax. Go and listen. Enjoy your music.

I know I may have rushed it, but reading about all the improved musicality of TT, I just bought on Audiogon, a like new Technics SL 1200G so it will work on my McIntosh MX 135 pre-amp which I understand has a MM phono stage.  

It is being delivered next week so I would like recommendations on a MM "starter" or more intermediate cartridge that would pair well with my new to me TT.  I listen to classic rock mostly with some classical as well.  

Any Grado would be a good match with the tone arm on the Technics!
https://www.needledoctor.com/analog/Phono-Cartridges/brand/Grado-Labs

Congratulations!  There is a huge difference as everyone says here with Digital sources.  You've skipped in my opinion the starter steps in what you've bought.  I am very inexperienced compared with all the guys here so I hope I'm not wrong here but as regards cartridge, I believe it's an even bigger influence on your sound.  MC vs MM ?    MM is perceived as lower end because the theory says that a coil is lighter than a magnet so can respond quicker to the bumps and troughs in your groove.   High Output Moving Coil cartridges can also be used into MM inputs although models are more limited.  Dynavector and Sumiko are examples amongst many.  You've a few days to read all the reviews.  Needledoctor is great source but read the descriptions because High Output MC cartridges are on a page labelled Low Output!   However, like all things its not black and white, MM can also be better than MC.