Get a teacher or tutor, here on Italki or elsewhere, if you can afford it, who can give you the help you need.
Write short texts for post on the Notebook section here. This way your grammar and sentence construction should improve as you learn from the corrections.
My own view - don't waste time in 'conversation' with those who offer to talk English with people who post here on Discussions looking for help. Unless they are either native speakers or at least advanced non-native speakers it won't help you. If they're not that good in English they're just wasting their own time and yours.