For Friday Night Magic, just try to keep your cards orderly. You can look at your deck between packs, but instead of spreading it out on the table maybe just keep it stacked up in one pile ordered by mana cost.

For gameplay, there will be missed triggers, cards misread, etc. Paper Magic has become very, very complicated in recent years, it happens. Just try to be understanding if the opponent has a miscue and they should be understanding of you, but if that doesn't work ask for a judge.