Summarize the following:
You don't want to draw too much attention to the fact that you'll be sleeping out in the open, since this might encourage someone to try to rob you. Wait until activity on the streets around you has died down a bit and be as inconspicuous as possible in setting up your camp. Note that many urban campers recommend you not use a tent, since this is very conspicuous. Feel free to skip this step if you plan on sleeping in your car and don't need to set up anything. Putting rocks or sandbags on the corners of your tent will help to keep it in place without being able to hammer it into the ground. If you can't pitch your tent on grass, try to find an egg crate or some other bedding to put between the tent and the concrete below. Whatever city you're camping in, there will probably be some potentially dangerous people out and about after dark. Your best bet for staying safe is to avoid these people entirely. At the same time, though, try not to slink, hide, or look suspicious in any way, as this will only call more attention to you if anyone sees you. In other words, you should try to avoid being seen, but if you have to be seen, try not to look out of place in the city. If you do end up interacting with other people after dark, don't accept any offers and try to disengage from the situation as peacefully as you can. As long as you aren't doing anything illegal and don't look suspicious, most police officers will not bother you while you're camping. However, if an officer does approach you, be honest and forthcoming about your activities and don't act like you have anything to hide. It helps to make absolutely sure that the way you're camping is perfectly legal. This way, you have no reason to be concerned about interacting with a police officer.

Summary:
Begin setting up your campsite just after nightfall to avoid being seen. Place your tent on grass, if possible, and weigh down the corners. Avoid other people as best you can without looking suspicious. Do not try to avoid engaging with police officers.