How to Copy Someone's Handwriting. A person's handwriting is as unique as her fingerprints. Rarely do two people have the same handwriting. That is, unless the second person is intentionally copying the handwriting. Copying handwriting is a simple technique that takes a great deal of patience and a good eye for detail.
Acquire a writing sample of the handwriting you wish to copy. A signature is a bad place to start, since most people don't use their natural handwriting in a signature. Find a letter or a memo which ideally contains all the letters of the alphabet (and many different transitions between two letters if the writing is cursive).
Write out the message you want the person's handwriting to say on a separate sheet of paper.
Compare your message to the writing sample. Look at every letter you need to copy and the transitions between letters. Watch out for the quirks of the handwriting, like where the letters start and end, the size of the loops and how rigid the flow is.
Copy the new message, letter for letter, on a new sheet of paper. Take a lot of time to emulate the writing sample. If you must, lay your paper over the writing sample and trace each letter. This will not work as well for cursive, which requires transitions, but you can master the basic shape and style of each letter.
Check your work for accuracy in comparison to the original. Take a break from the copying and clear your mind. Come back to the letter with a clean head and compare both works to see if you need to repeat the copying process.