how i try to improve my pronunciation

I have the same situations about my pronunciations like your guys. You never know how terrible I am when I have to repeat 1 word for more than hour and a half ,none stop. That word''s "mixed". My manager repeated so many times, he tried to find other similar word for me to speak. I think I''m crazy at that time. I tried really hard, because it''s shamed when I talk that word and someone do not understand, so I have to improve myself. repeatition so many times, when you are alone, taking shower, driving, every where you are... I think it''s really a best way for improving pronunciation.
Repeating 1 word first, then try a whole sentence...until you feel comfortable to talk that sentence...
Now, I have to repeat the word "Arnold Palmer"..the name of the drink: by mixing of lemonade and ice tea.... Palmer I can say, but Arnold,still wrong...
If you have any idea, please reply...Thanks

To pronounce correctly, we need to know how to pronounce all the English sounds, syllables (phonetics) correctly and how to speak phrases and sentences (intonation, accent training) . For phonetics part, we need a good pronunciation dictionary.
For example, according to dictionary the word mixed should be pronounced as /mikst/ . Then, we pronounce /miks/ + /t/. If we miss /t/ part (for -ed), people won''t understand it as the word ''mixed'' but ''mix'' (/miks/).

My pronounciation is like a mess, but it''s still better than ....speak out nothing
Use the similar words to avoid some of difficult ones, is that ok?

using the similar word first then be back to the first word, that''s the way my manager does. I think it''s work. Then, keep repeating the first one until you can.

It''s difficult for someone to pronounce a specific word or a group of words correctly. But others can. So go seek help from them. Repeating a single word thousand of times will drive you nuts! Don''t try that, communication skill must be improved based on a more interactive way.
You can try either one of these or both.
1. Listenning to Rap/Hip Hop music. Even if you are not aware of what they are talking/singing about, pretend that you know and you shall gain more confidence by trying this method.
2. Watching US movies. Learn the way they talk and mix our cultural experiences with them. I am not urging you to join/manipulate their culture with ours. Learn the best from them and speak English like the way they do.
I have seen so many of my friends, who are from the North(ie Hanoi) speak English using pure Vietnamese accent, and frankly telling you guys, it''s not so pleased to listen to those kinds of English.
One more thing, for a specific word such as "mixed" or "Arnold" in your case, best thing is to consult helps from native speaking people from universities, they won''t refuse to help a nice girl who wanna improve her English
All the best for your English skills

Watch more TV shows and news in English . Have you guys ever wondered how Vietnamese American kids can speak perfect English without going to school or having any English-speaking friend? They watch 10 hours of TV every day