Unless I have taken bashing as a skill, I usually start by making a wooden spear from a thick branch using the pocket knife I started with. Then I find a house on the outskirts of town, make sure there’s no nearby zombies (usually isn’t at the outskirts), and break a back window. Just in case, I wait a bit to make sure nothing aggro’d. If so I lure them into a bush to slow them down, and stab them until they stop moving. Clear the glass from the window when it’s clear, and loot the house, trying to avoid the front windows as much as possible.
Usually you can find at least a few crucial items in the first few houses. You can make your way around the edge of a city doing this if necessary - you’re unlikely to attract any attention that can’t be handled with a window or a bush and a wooden spear.
I’m not sure why it was suggested to break the door down instead of windows as a) it still makes noise I believe, b) is facing where the zombies likely are so you are exposing yourself to sight lines, and c) is marginally closer to where the zombies are, making any noise you make travel that much deeper into the city. It’s not a huge difference but it can be the difference between attracting a horde if you’re unlucky.
Honestly it is extremely rare to attract zombies at the edge of a city with breaking glass. And any that do come won’t be a huge hassle as long as you have SOME weapon and make sure to use obstructive terrain to your advantage. Get 'em tangled up in a bush or crawling through a window and you’ll get some free attacks.
From there you can kite zombies out of the city center by being careful in how you reveal yourself. Poke your head into an alley between two buildings and you can grab a slice of a horde, pull them back out of noise range and deal with them at a chokepoint. Doing this enough times, you can make an ordinarily unapproachable part of town safe and zombie-free, and give you access to that gun store or military surplus store you desperately want access to but were death traps before.
