With most of these questions, the issue boils down to PREPARATION. How well a player is prepared to play in various situations, against "better" competition or against "lesser" competition, makes all the difference. I didn't use to believe this, but I do now - you play like you practice. You need to practice being in the important game, behind by a goal with seconds left and the play is designed for you to take the shot, trying out for a team, or with your parents in the stands. All of these scenarios, and many more, if confronted directly will prepare you by knowing you have overcome them in the past. With this increase in confidence you will play with less apprehension and "nerves". There is a reason Tiger takes a bucket of balls in the woods or the rough and practices hitting them out of the worst conditions - to prepare him in case he ends up in that situation!

An "important" game is given that description when the outcome is given more weight, or there are special circumstances ascribed to a win/loss. If you didn't know it was the "finals" would you play differently? You shouldn't. All games should be approached in the same manner - with the same preparation. Not only is preparation at the the foundation of peak performance, but that consistent preparation also serves to put you in the same "headset" associated with playing at your best.

You really don't want to get rid of "nerves". Rather, you want your nerves to work for you - not against you. I once asked a professional basketball player how he manages his "nerves". His response was, "I don't feel nervousness, I have butterflies".  His reply speaks volumes about how the way you interpret an event is how your body will react. Nerves are related to thoughts - how you think is how you will feel. Control the thoughts and you have a better chance of feeling the way you want and need to feel in order to be at your best. This can only be accomplished by good preparation/practice.

Again, how prepared are you to manage your mistakes? When was the last time you practiced recovering (mentally) from a mistake or a bad shot, or a blown play? I encourage athlete's to develop and then make use of their own Mental Recovery Device (MRD). This consist of learning how to calm the body and re-focus the mind in order to return to your optimal level of performance. These techniques make use of learning how to calm the body through breathing and letting-go and  making use of  restructuring thoughts in order to re-focus on current events; not what has happened or what may happen but what is happening now.

From what has been described so far the obvious answer is yes. These exercises have to be practiced prior to competition. Practicing these however can be somewhat tedious unless you are convinced they will help you in the same way you are convinced weight training or riding the bike helps you get physically stronger. As mentioned previously, these exercises should be practiced on an on-going basis not just before the "big game". In fact doing these just for the "big event" would only heighten the magnitude of the event and probably won't be successful and thereby creating even additional anxiety. Practicing these techniques (MRD) on a regular basis, using a step by step format will not only ensure the successful learning of these skills but will also raise the level of expectation of success (confidence) in competition because the athlete will "know" he/she is prepared for anything that might occur during competition.

At the risk of being redundant the best way for an athlete to be more consistent in their play is to learn how to focus and maintain that focus - no matter what! Even though external conditions, events, or situations change, maintaining a consistent internal environment is the key to performing consistently. Not getting rattled, not getting to excited or to low during competition, preparing to come to competition the same way everyday. Inconsistency in youth sports is somewhat age-related, but if an athlete is wanting to best-at-their-best, there are ways to ensure this and that take.....you guessed it.... preparation.

I have said many times over the years of working with professional and elite athletes that once you arrive at the competitive venue...the field, rink, court, track, whatever...your physical state is a constant. This means you are as physically strong as you will be for that game. No more work outs or strength training. In fact over the course of the match or game you may even experience fatigue, thereby having even less physical resources available to you than when you began. Mental skills however do not have to follow the same progression. Yes there is mental fatigue as there is physical fatigue but mental fatigue unlike physical fatigue can be overcome during competition whereas physical fatigue requires much more time for the muscles to recover. Therefore, mental toughness is something that can be altered during competition. The athletes that know this and learn to control what they can control, i.e. their mental processes, are indeed better prepared to endure what is needed to achieve consistently higher levels of performance. The physical attributes get you to the "dance". The mental skills have you "dancing" better and longer.

It goes without saying, what you fuel your body with and how well you maintain good sleep habits will affect your performance. The types of fuel, the amounts of fuel, the regularity at which you  fuel are all important factors to peak performance. Good luck convincing a kid of this!!

Most certainly. This is an area that needs much more attention these days. Parents generally want to do the right thing but unless a parent understands how their behavior effects their child they continue to do what they believe is good for Johnny but in fact leaves lasting emotional obstacles for Johnny to have to overcome in order to be successful on or off the field.

Whew! There is no easy way to build up self-esteem if it has been deeply trashed over a long period of time. Minor dips in self-confidence or the occasional "lows" experienced by young athletes can often be overcome by talking with a trusted advisor, usually not parents, who they trust to be a straight shooter. Replenishing the ego is a more complicated process than this forum can offer but as you mention, key phrases, thoughts or sayings, visualizations can evoke a calmer mental state or return one to their optimal level of performance. Again, this takes practice and preparation in order for it to be effective during competition.