Now that jail authorities can strip search you even if they don't suspect you of carrying contraband, etiquette is especially important.and this
This isn't an etiquette matter so much as simple preparedness, but if you at all think you're going to get picked up, say at a protest, you should be prepared. Make sure you have some quarters to call out on the jail pay phone because they'll take your cell phone when you're getting booked in. Write the phone numbers of anybody you might need to call on a slip of paper. Dress in layers, because jail temperatures can really fluctuate, and wear comfortable shoes because you may be standing for a long time in a crowded cell. And if you can, give your cell phone and other valuables to someone before you're taken away, so they can bring it to you when you get out and you don't have to go to the precinct to collect it.This sort of thing should not happen in a free society. Some percentage of the people who get arrested are actually innocent. Others may have broken the law but are innocent of any wrong-doing or wrong intent. It just isn't right to give the police power to make their lives miserable before they've ever seen a judge.
Law-makers and law enforcement should think about what basic level of decency they would like to see if they or their family members were arrested and enforce those rules. I think some reasonable ones are the following:
(0) the cell should be clean, with good ventilation and a comfortable temperature. And not smell like urine
(1) everyone gets their own chair and it should be comfortable with reasonable padding and back support
(2) people who have gotten violent or extremely belligerent should be locked up in a private cell. It's not fair to just separate these people from the others because that just means the weaker ones suffer. If there's not room, they should be handcuffed to their chair in the common cell and a police officer should be present and observing at all times.
(3) private restrooms and private phone calls except for people who have been arrested for serious crimes or there is some other reason to be concerned about escape attempts or suicide or (in the case of the calls) criminal conspiracy
(4) no strip searches unless they have been in prison before or there is some other reason to suspect that they might be hiding something dangerous or illegal.
(5) they should be able to keep their cell phone or at least ask for their cell phone to make calls.
(6) they should be able to keep food, drink and entertainment or work devices such as books, magazines, laptops, ebook readers, mp3 players, and game pads as long as they keep them quiet.
(7) outside friends should be able to bring the above things to them
(8) anyone there for more than (say) 6 hours gets access to a safe, clean bed to sleep on.
Of course, all of the above should be limited by security issues, and there are difficulties involved in administering this. It's expensive to make rooms both secure and large enough to have chairs and beds for everyone and to make sure that things don't get stolen. But if you are going to limit someone's freedom on suspicion only then you have a responsibility to make it as painless as possible in case your suspicion is wrong.