A handwritten signature in Word
Drop your signature into a DOCX exactly where the signature line already is.

A DOCX is a layout that reflows, so a signature pasted in the wrong way moves when someone edits the paragraph above it. Placing it at the signature line, at a fixed size, keeps it where the document expects it.
Getting the mark off the paper
Write on unlined white paper with a dark pen, photograph it straight down in daylight, and let the background be as bright as possible. A handwritten signature in Word start here: everything the software can do later depends on this one clean capture.
Use a transparent image rather than a white photograph of paper. On a coloured or bordered page, the white rectangle is immediately visible and makes the whole document look assembled.
Placing it on the document
The finished signature should be a transparent image, cropped close, sized to the signature line rather than to the page. A white rectangle around it is the single most common giveaway that a signature was pasted in.
When the file is going to a third party, send a PDF. It preserves the position, and it stops the recipient from editing the text under your signature.
What makes it hold up
What usually matters in a dispute is not the beauty of the mark but the trail around it: who sent the file, when it was signed, from which address. The drawn signature is the visible part of a much longer record.
You can build any of these in the browser: open the Signature maker, draw or type your name, and place the result straight onto a PDF or Word file. Nothing is uploaded — the document never leaves your device.