The most important step when accepting criticism is to take it seriously. If someone has a suggestion or a complaint about your game that you haven't already considered and resolved, write it down. This has the benefit of letting you come back to it when you're not trying to run demos, schmooze with the public, or worry about any of the other things that might be going on at that exact moment. In addition, some ideas that may not work at all for the current iteration of your game might be perfect once you've changed other things later in your development process. Even if a suggestion seems great right off the bat it's worthwhile to take some time and consider it from all angles. It's just as bad to give in to all feedback as it is to ignore all of it. At the end of the day you have to be able to make an educated call as the designer of the game- if you aren't able to separate bad ideas from good most of the time then you've probably got a long road ahead of you before your game is ready for publication.
When getting feedback on your game you have to consider why you are making it in the first place. If your goal is to make your game the best it can possibly be you can't just ignore criticism. Remember that criticism doesn't just mean that someone doesn't like your game; it means they are invested in you and your projects, and they want to see you succeed. It's much easier for a person who is uninterested in a game to simply ignore it and move on. Appreciate the critic, because their investment in your project is something you should not take for granted. Your game will be better for it, and you will be much more successful when the voice of your audience is heard.