Chess Principles to follow

Chess is hard, we all know that chess consist of theories and opening lines which can be found in the internet or various chess books.

However sometimes we may find ourselves, especially beginners struggling to find the right move which leads to blunders and mistakes that may lead to loss of material or loss of a game itself.

Whenever we run out of theory, what are some common Chess Principles that we can follow and apply during our games? What are some chess principles that can help prevent blunders, bad moves, finding the best moves in games, tactics and ultimately principles that can help us win games without struggling to think or calculate intensely. Just seeit as a simple reminder/advice when there's no hope left.