I am just finishing the conversion of my back yard shed into a coop! I like it better than other coops, because it is bigger - much more space for them to, y'know, be chickens.
I made a pop out door that is also a ladder that leads to their run and secured it with a locking latch. Made several roosts about 2.5 feet high going across a corner and used old cantaloupe crates for nesting boxes (I actually, in a fit of craftsmanship, built a 1 foot high, um, "table" to put the cantaloupe crates on) - I secured everything with screws. I also took an old reclaimed window and installed that on the southern side.
I also cut out two windows on opposite sides - about 4 feet up- and covered them with wire mesh (think sliding door). They can be opened when it is warm for ventilation - but there is also ventilation along the top where there is a gap between walls and ceilling. I put wire mesh along those to keep rats/squirrels/undesireables OUT!
I also whitewashed the inside and will paint it yellow (latex, of course) because I heard somewhere that they lay more with yellow painted walls (dunno - we'll see!)
I am also going to do a deep litter method and still need to figure out how to hand the feeder, secure the water - they like to scale both of those!
Just make sure any windows/openings are above where chickens will roost and that the nesting boxes are off the ground and all will be well! I gess maybe no openings on the windy hill side because drafts are bad.