There are two "areas" to be worked on: anatomic functionality (1) and psycholinguistic processing (2).
(1) Stick your tongue out and try to vocalize as high as you do with your tongue in your mouth ( assuming that's where you keep it when you vocalize ). Can you go as far up? If you can't, try to practice with it out until you're able to do it. That helps disengage the tongue-related muscles from ALL and any vocal production you make. With it so relaxed, it's easier for its tip to move independently from its back.
(2) Concerning that "r", it's basically American voiced /t/ as in atom, when it's similar to the /d/ as in Adam. It may be easier for your nervous system to "accept" keeping on "atttttttttttttttttttttttttom" rather than "carrrrrrrrrrrrrrrrrrrrrrrrro amigo mio", as it already "knows" your /t/.
Best wishes,
Caio
|
| |