You must have "something" that is defendible in court giving you rights to lien. What that something is depends upon the reason you want to lien. You should refer to the state's lien laws for specifics.
Laws vary by state and my comments are based on California law. There are many procedures that might apply depending on the type of lien you are referring to. If you have a judgment against someone...
A Judgment Lien is a lien placed on property by a creditor to recover a certain sum of money granted by a judgment awarded in court. The property can not be sold legally while the lien remains unpaid.
A Mechanic's Lien is also known as a Construction Lien. Construction Lien rights are available to anyone providing material, labor or services for the improvement or repair of real property. To...
Liens.
Basically a lien is a legal instrument giving a person, business, etc. the legal right to take, hold or sell another person's property for debt or restitution of some sort. There are many...