Even if you use codes to prevent downloading from sites people can use screengrabbing programmes. Small images with low dpi is what I normally do. In the case of my first upload, here today, that was the worst image from 150 I took yesterday.
don't trust that thatmuch... you can download the freeware Brigitte or Birgitte (I do not remember), or any other similar software and copy any pictures you want from internet... and sometimes teh codes for avoid downloading do not work if you use Mac
so I agree with Ray and Ross: smaller pictures and a the copyright on it (I have never been able to use "watermark" - Thanks for the link to the tutorial, I will have a look on it )
How do you do the copyright symbol? c in the circle!
Thank you.