The other two comments have great advices, but also you could really really try to focus on an specific sound. I mean not only a word but specific consonants and understand how they are anatomically generated in your body.
For instance: the R sound. In French it's almost completely generated through your throat with your tongue laying down below the level of your teeth. In Spanish the sound is almost completely generated by your tongue which should be lift up and touching your upper teeth with the tip, in English it's exactly the same movement with your tongue lift up, the only difference is that the tip of your tongue should be a bit -just a bit- in the back of your mouth and not on your teeth. So practice, put your tongue in Spanish R position if you are already familiar with that sound (or just do it as I detailed it) and while still producing the R sound get your tongue a bit to the back and it will gradually -instantly- sound as an R sound in English. Best of luck. :-)