I taught English to Japanese children, and the best way to improve pronunciation was to watch their mouths closely and tell them where to put their tongues. For example, they would say "sankyu" instead of "thank you". I would repeatedly show them the "th" mouth (putting my tongue in between my teeth). For the difference between the "L" sound and "R" sound, I would open my mouth big enough so they could see. (making them sing lalalalalala and having them make growling noises for "R" helped too) There are websites and videos online showing the mouth shapes and tongue positions. This is tedious but rewarding! This is actually something my Chinese professor made me do as well for Chinese. He would come around the class looking into our mouths to see if our tongues were in the right place! You can do this with a mirror or video! Good luck!!!

From the standpoint of writing, I can tell from the essay if it is written in Chinglish or not since I know Chinese well enough to translate them in my mind. There are two types of Chinglish, one form is used by native speakers to stereotype and become part of English. For example, "No washy, no ticky", "Long time no see", etc are accepted forms. The other type is because of differences in culture to express things. One of the best ways is to do translation, from Chinese to English and also from English to Chinese. You can see the difference in how things are said in both the source and target languages. An exaggerated example is 我的心肝宝貝, it would be not be understandable if you translate it as "My heart & liver, precious shell (money)" instead of "My precious darling". Another example, to translate "冰凍三尺, 非一日之寒"? Hint: Think of 罗馬... When you have finished translating, post it here on italki and have it corrected. This way you learn faster. As for learning from movies, songs, etc, also you have to beware of the quality of lyrics used. Just because it is popular, it doesn't mean that they are good. If you are not careful, you mean speak like a gangster, a prostitute or just some fisherman's wife in the wet market.

You can train your mind to think in English and stop translating from Chinese. With a period of practice, you should be able to get rid of the chinese way of speaking in English.

Try to do a correct pronunciation with the letter "R"... like Rome... Is useful when you speak with a foreign chinese people.

Other than the obvious (lots of conversation practice with native speakers), watch a ton of movies (best to pick one sort -- American or English or Australian or whatever) without subtitles. While watching, pause numerous times to repeat particular phrases that you hear. This is just one of many possibilities, but the maybe the most DIY.