Entries

Entries can be as important as your high cards for the self-evident reason that if you don't have entries to (apparent) winners, then those aren't winners -- and might as well not be high cards. Like any topic in bridge, there are going to be hands where very delicate decisions must be made and situations not clarified until half-way or further through the hand. Nevertheless, I say, not all decisions, not even most decisions are going to be all that delicate, and one of my underlying philosophies is, "Let's not miss the easy ones.".
I would say two basic principles to keep in mind are, (1) don't use up entries recklessly when you don't need to and (2) to the extent that you feel the press of play and the hand isn't clear, you'll want to keep entries in a hand where they are scarce and where you expect to have some good tickets later in the hand.
Well, here are some examples:

One Two Three Four
Five Six Seven Eight
Nine Ten Eleven Twelve
Thirteen Fourteen Fifteen Sixteen
Seventeen Eighteen Nineteen Twenty
Twenty-one Twenty-two Twenty-three Twenty-four
Twenty-five Twenty-six Twenty-seven Twenty-eight
Twenty-nine Thirty Thirty-one Thirty-two
Thirty-three Thirty-four Thirty-five Thirty-six
Thirty-seven Thirty-eight Thirty-nine Forty
Forty-one Forty-two Forty-three Forty-four
Forty-five Forty-six Forty-seven Forty-eight