Most people read the main form, see the familiar headings, and assume the rest of the paper says the same thing. That assumption is where surprises start. Riders, amendments, and add-on forms are often printed separately, handed over in a stack at the end, and written to change a section you already skimmed.
Count every page you are asked to sign
Before you put pen to paper, ask the seller to list every document in the package by its title and its page count. Then check that the stack in front of you matches the list. A missing rider is not a reason to relax. It is a reason to ask where it went.
Look for words like replaces, supersedes, and notwithstanding
These are the words that tell you a later page overrides an earlier one. Read the sentence that contains them slowly. Ask the seller to point to the original clause being replaced, and ask whether the replacement is for your car, your state, or every buyer. If the answer is vague, the clause is not ready to sign.
Check who initials the changes
If a handwritten change or a typed insert appears on a form, confirm that it carries both your initials and the seller's, and that the same change appears in the final copy. A change you did not see being made is a change you cannot rely on later.
Get a complete copy after signing
Ask for a full, legible copy of the signed package, every page included, before you leave. Put it in the same folder as your purchase paperwork. When a claim comes up months or years later, the copy you can actually find is the one that decides the question, so make sure it is the complete one.
Our notes on how each company's form is organised are in the individual fact sheets on this site. Use them to see which documents a company typically asks you to sign, then compare that list against what the seller hands you.