Pronouncing R like the French

I need some suggestions on how to pronounce the guttural R. I have no problem saying très bien but très by itself is next to impossible: 98% correct first try for the former and 98% wrong for the latter until my jaw and head hurt; same goes for trois by itself but no problem if it has a second word like trois cent.

What's your secret? Please share. 

In the past I studied both German and Spanish and was pretty good with each language.  I even lived in Mexico for a time.  Those two languages also each have the guttural R, and I never totally mastered it; I tended to roll the sound off the tongue rather than in the throat.

Because the sound isn't familiar to the English tongue, it's a hard one to master, as you've pointed out, M-L.  If you really want to say the sound correctly in your speech, I think it will only come with listening and practice.

Diana-S1,

Thanks for the advice, the good old try try again approach. I know one day I will be able to speak the language but for now I need some relief, real relief from jaw/head/neck pain just from trying too hard, like repeating 50 times on très alone a few days ago. 

I tried gargling with water as a way of getting the trill but it was like doing research in the lab where it worked wonders but didn't translate to clinical performance when I have to say it to the recording device. 

Being a beginner I'm a little discouraged, that's all. 

Have you tried Cheryl Demharter's "French Sounds" series? My tutor recommends her work to students looking to improve their pronunciation. Here's one specifically for 'R' sounds:

https://www.youtube.com/watch?v=quiez2Y2gcM

(Sorry, there doesn't seem to be a way to fix the hyperlinking on this interface)

 

That's a good video.