If you have a hotel lock, if ICE knocks on your door, you can ask to see the warrant, without letting them in.
Have the ICE officers slide the warrant under the door or under the hotel lock. Take your time to read the warrant. If the warrant was signed by a judge or magistrate, see what it gives the officers permission to do - arrest a specific person, or question people and inspect the place? If it appears valid, they have the right to come in - but make sure they only do what the warrant authorizes. OR, it is an administrative warrant? If so, ICE can only enter if YOU give permission. Do not give permission - you don't have to open the door.
Do not answer any questions.
Tell ICE you want to speak to your attorney. Have the number of a trusted attorney on hand, perhaps programmed into your cell phone, so you can call her in an emergency. Unfortunately, since immigration law is not criminal law, there is no public defender, so you will either need to find a free attorney or hire one.
If you accept voluntary departure, you can be deported immediately. It will be very difficult for you to return to the United States if you have lived here illegally. If you have been here over 1 year without permission, there will probably be a 10 year bar for you to come back, and getting a waiver is very hard. If you live in Southern California and are from Mexico, you could be in a bus by nightfall. So, do not accept voluntary departure.
This will help insure that your case will not be transferred to another, far away, court.
If you insist on your right to an immigration judge, you will be instructed when and where to appear in immigration court. Make sure you show up, or else you can be deported in your absence. Make sure you keep your address current with the court, so they can inform you by mail if your court date changes. It is advisable to find a lawyer - there are some free lawyers - who will represent you in immigration court. A lawyer is indispensable because there are many complicated ways for you to try to get a green card and stay in the United States legally.
You can keep this card in your wallet, and it comes in both English and Spanish.