Placement errors are one of the reasons speech sounds accented. If you are making sounds in a slightly different place in the mouth, your speech will sound different than a native American English speaker(for example some languages say "t" and "d" sounds with the tongue pressed against the back of the teeth, while American English we press the tongue against the alveolar ridge (the ridge on the roof of the mouth behind the teeth).
Choose a few words with consonants from each of the places of articulation. Are some more difficult for you than others? What about moving from place to place?
Bilabials: mom, people. web
Labio-dental: five, vie
Alveolar: tiny, lot, says, not, don't
Palatal: shoe, chew, judge, rich
Velar: kick, gag, king, going
Glottal, hi, he
Mixed: beet, peek, wing, push, chip