If you are very well dressed and also have the charisma but not communication skill up to the mark, it may leave a blot on your personality.
When you speak to the other person, make sure you look confident in what you speak and hold the intensity in your voice. If you speak in a dull voice, the person opposite may lose interest in the conversation.
What language you speak doesnt matter. What matters is how clearly you speak. Pronounce every word clearly so that it is audible.
Cling on to your fluency. Be smooth and be calm in the speech you deliver. No need to rush. Always let your mind lead your tongue.
Take regular pauses in between. And emphasize on respective words that you need to highlight in your speech.Whenever you stop while speaking, replace words like ummm and aaaa by your silence.