First of all, you have to have a course on pronunciation with lots of exercises. They usually provide some very simple pairs of words like mite - mate, good - god, lard - lord etc. Then take some tongue twisters and try to pronounce them first very slowly and then speed up. Tongue twisters like: Peter Piper picked a peck of pickled peppers. A peck of pickled peppers Peter Piper picked. If Peter Piper picked a peck of pickled peppers, Where is the peck of pickled peppers Peter Piper picked. Also songs are great pronunciation helpers, sing songs it will create a good mood and exercise your tongue at the same time. Good luck. :)

Try this face... http://englishphonetics4u.blogspot.com/

国际音标没有学好，从头开始学习音标，掌握辅音与元音之间正确的衔接，以及元音与元音之间的合理连接，这是很有讲究的，单纯读单词，每个学英语的人都会，要是把单词连接起来，成为一个成体，里面的学问很深的，比如给你举个简答例子：sugar and jam 这里的每个单词你都会读，要是在一起，估计你不可能读的十分准确，甚至会单个往外蹦着说，这就是学英语不能停留在学单词的层面上，英语的读和写在很大程度上是不统一的，尤其是对于中国人。毕竟拼音要落后国际音标100年的历史。