I have a Masters in (Descriptive) Linguistics which is the study of patterns of both grammar and phonetic patterns of languages. This, combined with a summer course at Middlebury College in Vermont on comparing and contrasting the sound systems of French and English speakers, has given me the training to help speakers of these two languages correct pronunciation difficulties. There is even a slim textbook: "Le Français Sans Fil" that we used at Middlebury. One example is: "piano". English speakers include a "y" sound between the vowels, "i" and "a". French speakers do not. Also, to help an English speaker contrast the sounds "ou" and "u" as follows: "ou" has tongue back and lips rounded; for "u", start with "i" and then round lips without pulling tongue back.
Finally, there are definite sound/letter correspondences in French which can be systematically taught similar to English "threw" and "through". And in French "au" = /o/ and "en, in, on, un" are nasals, so put the tongue down -- English speakers automatically put the tongue up behind their top front teeth for the letter "n".
Don't worry. As my student, you don't need to know these patterns but I use this knowledge to help you learn the sounds and then teach your ear to help you monitor their correctness.