Deckbuilding: It's hard to give general deck advice, but two things to note are that consistency is a big deal and that you should make an attempt to predict your meta. Inconsistent decks won't win tournaments, and predicting your meta can give you an edge on what deck to play and what techs you should use (if any, again, remember consistency > techs in most situations).
Places to practice: I can't help you much here, there are tons of great ways to practice. Just make sure to do a lot of playtesting ahead of time and be familiar with your deck and how it plays.
Environment: I'm not sure what you mean....
Arriving: I get to tournaments 20-30 minutes before registration because I like to playtest with friends, but I would highly suggest being there at least 10 minutes early even if you don't want to do that. You'd rather be relaxed and not be rushed when you get there. Printing out a decklist beforehand saves a ton of time also.
Concentration: Just put your mind in complete focus of the game. Ignore all outside sounds, noises, and distractions (unless it's a judge) and simply focus on what is going on and your best plan to win. Listening to music beforehand or doing something else to relax also helps.
Penalties: Just follow the rules, and if you're unsure of something, always ask a judge. You'd rather be safe than sorry. Remember to not mess up silly things like forgetting prize cards or showing your hand after whiffing basics.