Prison Architect/Tips

You may want to..

Build a holding cell
Set up a holding cell and padded holding cell, even if you think you have enough cells and/or don't accept criminally insane (psych ward DLC) inmates. If "room quality" is enabled and all your cells are high quality, some prisoners may not be assigned a cell because all the cells are too high in quality for them. When left unchecked, prisoners without a cell can easily become criminally insane.

Make a reception area
It's optional, but this ensures newly arriving inmates are searched for contraband before entering your prison.

Cluster rooms with contraband
Cluster all rooms containing contraband together (see "dangers" under "intelligence") that prisoners may need to access and set up a buffer room with metal detectors and assigned guards and dog handlers between those and the cells.

No prisoners in the laundry
Don't use prison labour for the laundry. Janitors are cheap and the laundry contains rope which somehow can be used to dig tunnels while being impossible to detect with metal detectors or dogs. Make the laundry room staff-only (deployment) and make sure that the hallway or room it leads into is also staff-only so inmates can't easily slip in with the janitor.

No wandering around in the staffroom, get back to your cell Jimmy
Likewise, make sure to mark every room your prisoners don't need to enter as staff-only.

The criminally insane want luxuries
It's a bit unbalanced. You generally can't properly cater the "luxury" needs of your criminally insane inmates. They need to visit a shop to satisfy this need, but if they arrived as a criminally insane inmate (as opposed to becoming one), they typically have very little to no money and they can't work. There might be workarounds, but those will probably have unfavorable side effects. Untested, but for example they might be able to earn money if you allow them to steal and trade contraband.

Greedy staff going on hunger strike
If you have enabled (disabled by default) "staff needs", you may find your staff starving after a while and even demanding a raise and going on strike otherwise. This despite dozens of staff meals being available! The problem is in the food trays. A cook must wash the dirty trays in a sink and put them back on the serving table. This is kinda buggy. If your staff room (with serving table) or staff canteen (a regular canteen marked as staff-only in deployment) is small and/or the benches/sofas are near a wall, the staff may leave the dirty trays somewhere just outside the staff room. Placing sinks near where the dirty food trays are left may help. If there are dirty trays on the sink but the cooks aren't operating the sink, hiring a new cook and spawning them directly in front of the sink may help.

Janitors/workmen/gardeners faffing about the storage room
If your janitors are not cleaning the prison but instead just faffing about storage/deliveries/garbage/exports areas, you have a problem. The exact cause is unclear. It might be caused by some area of your prison being inaccessible (like some outdoor area or abandoned building you have completely forgotten about) and the staff suffering from extreme compulsion wanting to clean that area you don't care about first. Check your deployment screen to see if any areas are inaccessible. The problem might be helped temporarily by erasing the storage area, but eventually you may find your staff breaking down completely and attempting to escape the map. Which clearly wasn't any sort of intended behavior by the developers as they can't and they'll just be stuck in a corner of the map.