One practical safeguard is to keep images of your work on the Internet in low-resolution,
as this generally makes them unsuitable for printed reproduction. Internet images can be resized to 72dpi (dots per inch) without loss of online viewing quality; printed material usually requires a minimum of 300dpi for a good quality printed image.
If you need to send out high-resolution images(for example to submit an application or for press publishing) first check that these will be stored securely and not available generally on the Internet. If images are to be used online, such as on a gallery website, ask that they be resized to a low resolution, or do this yourself before you provide them, and request they be clearly captioned with your copyright information. Print publicity images will have to be high-resolution, but should always include a caption stating your authorship and only be used for the purposes you allow.
When sending the work you may wish to expressly assert your copyright, and the following wording can be used to achieve this:
"All rights reserved.
No part of this work may be reproduced or transmitted in any form or by any means or stored in a retrieval system of any nature, without the written permission of the copyright holder.
No part of this work may be modified, without the written permission of the artist.
No part of this work may be exposed to public view in any form or by any means, without identifying the artist as the author."