When it comes time for your party, make sure you pick the correct balloons. Going with the theme is the best options but if you do not have one then picking the favorite colors or what they like is another options. Always go with what you feel and what the balloon expect says. Make it a happy medium and go from there.
There have been times when a client changes their minds but it is ok. What I find is that they normally go back to their original idea and you as the balloon artist needs to add a little flare to the balloons. It is ok change ones mind but making it fun and easy going will have the client relax and trust you more.