Only one of them is fashion, and it is the least important of the three. Settle the other two first and the list below gets much shorter.
Your face shape decides the outline
A haircut is a shape you wear above your face, so it either balances the shape already there or fights it. A round face wants height and a tighter side; a long face wants the opposite, because added height only makes it longer. Work out which you have with the face shape finder, or read the reasoning in the face shape guide, then use the shape rows above to filter this library down.
Your hair decides what it can hold
Density, texture and growth direction set the ceiling on what a cut can do, and no product raises it far. A pompadour or a quiff needs enough hair to stand up and stay there — fine hair will do it for an hour, not a day. Curly and wavy hair carries shape on its own, which is why layered and mid-length cuts suit it and heavily structured ones fight it. Thinning hair is the one case where shorter genuinely reads fuller, because a crop is not asking for volume it does not have. If you have a cowlick at the front or a double crown, say so in the chair: they decide which way a fringe will sit, whatever you want it to do.
Your upkeep decides whether it survives week three
A tight skin fade stops looking like a fade almost as soon as it starts growing, so it commits you to regular visits. A scissor cut with no hard line grows out into something that still reads as deliberate. Neither is better. But choosing a high-maintenance cut and then keeping it for two months is how a good haircut turns into a bad one, so pick for the schedule you actually keep. Every cut page here carries an upkeep and length badge for exactly that reason.
Then ask for it properly
Naming the cut is not enough, because the same name means different things in different chairs. Describe the three parts separately: how short the sides go and whether they fade or stay one length, how much length stays on top, and what the front does. Bring a photo, and say what you are willing to do in the morning — a barber who knows you will not pick up a dryer will cut you something that works without one. Each style below has the wording written out for you.