This is the technique I use to teach my students how to pronounce the French "R". Hope it works for you.

French Kankan - Slow French

How to pronounce the French "R"

1. 地铁 - dìtiě - subway
2. 乘客- dìtiě zhàn - passenger
3. 换乘- huàn chéng - transfer
4. 安检- ān jiǎn - security check
5. 座位- zuò wèi-seat
6. 让座- ràng zuò - give up one's seat
7. 拥挤 - yōng jǐ - crowded
8. 扶手-fú shǒu-handrail