I'm late to the game, but like others have said, the first thing to master is a start from a stop on a flat surface. Once you get that down you've got the basic idea on how to move onto another gear which is much easier.
It came somewhat easy to me because I grew up with parents that both drove manuals (until my mom had to sell her 5.0 Mustang for a Mercury Sable for 4 doors). First vehicle I ever drove was a manual Ford Ranger. My dad was out in the pasture with me and my brother working on something (I was 10) and when we needed more water my dad did the sensible thing and decided to have me drive back to the house alone instead of going back himself. haha. He gave me a crash course of starting from a stop and then I just stayed in 1st all the way home and back. I practiced some more as I got older, but I decided I didn't want to drive stick and resigned myself to automatic. Bought one automatic car and drive it for two years, then another and got the mod bug and hung around internet forums too long and decided I needed to do a manual swap. So I did. And then I spent about 2 weeks learning how to drive my car again and then took the longest road trip I've taken so far from San Antonio, TX to Columbus, OH.
I currently have 6 years experience driving stick and I definitely have the natural feel for it, but I still stall it now and again.
I learned that the best way to actually learn ANYTHING is to get your hands on it and use it/work with it/break it/fix it. There were things I was taught in college that I didn't learn squat about because I never got to work with it. Got a lecture on it and took a test. That's not how you learn. The most useful stuff I ever learned about computers (what I went to college for) I learned from getting my hands on the stuff, taking it apart, fixing it. The same thing goes with learning how to drive a manual. It's great to read about it and watch videos for pointers, but even with all those pointers, you WILL stall the car. Until you learn how to not stall the car from your own personal hands on experience.
The best way to learn is in an empty part of a parking lot with no pressure to get out of anyone's way. Then you can just practice what people have been saying. With no pressure you can screw up and not have to worry about it. Just turn the car back on and keep trying. I got really lucky when learning how to do hill starts and managed to get it pretty well down before I ended up with someone behind me on a hill one day. It's really not better to just get the car going by any means if it means launching the car and spinning the tires because if you learn that that will definitely get you going without learning where the stall point actually is then you'll always try and launch your car and that's not real good on the car. That's why the no pressure situation to learn is so important. The best way to learn is to just keep trying no matter how many times you fail. You will get better, but you have to have the right attitude for it. If you tell yourself you can't do it, you will never do it. Instead of getting mad at the failures, take joy in the successes. Before you know it there will be more successful attempts than failed ones. And it's all in the feel, not the RPM, speed, or percentage of the pedal you let off. I hear people say shift at 3000 rpm all the time when teaching people how to drive stick. There's no hard and fast rule, that's just a basic guideline. The beauty of the manual transmission is that you can shift when you want. Every car is different. I don't even know when I shift on the RPM range for daily driving because I don't watch the tach, but it's higher than the shift light.
Also as has been said as well, don't shift into 1st until you're at a dead stop. 1st gear is so short that you can literally start the car from a stop in second. Not that you should, but if you're rolling even really slowly, leave it in second. Turns are a bit more tricky. Depends what speed you're going. I still miscalculate that sometimes.
As for those who say don't leave your foot on the clutch while at a stop because of throwout bearing wear and tear...the way I understand it is the pilot bearing is running with the pedal disengaged anyway so you're wearing one or the other. The throwout is the beefier of the two. The best argument for not holding the clutch pedal at a stop is that sometimes you may not be aware but you might not have the pedal pushed down as far as it should be and you might be slightly wearing the clutch. I prefer to be ready to go so I hold the clutch at a stop. If something is headed towards me ready to crash I don't want to be in neutral if there was a way to drive out of it. I've had enough close calls with different things that I don't want to be caught not on the defense. I drove like that in my old car for 5 years and something around 60k miles on the bearings I put in with the new clutch and transmission swap until I sold it.
Here's a girl that just bought her ST that I followed for a bit awhile back. She was still learning but she was trying.
[video]https://youtu.be/P2hXCv04LjE[/video]