The best way to really improve your French is to get plenty of practice. Most people worry about making mistakes or not understanding French words and this holds them back.
When you come to France on holiday, if you’re not au fait with the language, bring a simple phrase book –you will find it very helpful and it will endear you to the French people you talk to; even if you say things wrongly, they hardly ever laugh out loud at your funny pronunciation (well at least not in front of you anyway).
In some parts of France, you can encounter quite a strong regional accent and people can use different words from those you may have learned in traditional French. For instance in the North of France, Patois may be spoken. Coming across different words unexpectedly can really throw you so you should try to have a sense of humour about it and don’t get flustered.