Also known as Packing Tape transfers, these are easy & simple to do. 

Choose an image, place a strip of clear packing tape (eg: Scotch brand - the wider the better) over this, trim around the tape then burnish well with a bone folder or the back of a spoon, etc.  Also successful: self-stick clear plastic (eg: Fabulon) and embossable self-adhesive window plastic (rubber stamp stores).

Avoid lots of white space around the image - trim it off, as you will be rubbing all of this away.

Throw the image into a bowl of water and allow to soak for a few minutes. 

Take out, and start rubbing on the BACK of the transfer (the paper) with the pad of your finger (no nails!) and the paper will pill up so that you can roll it away and thus expose the image (the toner is now bonded to the back of the tape).  Keep dipping back into the water, and keep rubbing until all excess paper has disappeared.

Allow to dry, check if there is a suggestion of white "bloom" (see picture at left) this means you need to wet the paper and rub away yet more excess.

Allow to dry thoroughly before sticking down to your page. Often the tape is still tacky once thoroughly dry, so should stick straight down without needing any more adhesive. If you do need to use more adhesive, I recommend PVA or gel medium (these dry clear).

This method works with: newsprint, Sunday supplement magazines (the ones with paper most like newsprint, not the highly glossy ones) and most paper images (old sewing patterns, diagrams from old books). Also most photocopies (especially the cheap toner-based ones). Experiment with laserjet prints - most will work, but some won't.  This method does not work with inkjet prints or highly glossy paper (eg: those very expensive fashion magazines) as it is virtually impossible to get the paper wet enough to rub away successfully.

If you don't like the shiny finish that comes with packing tape and plastic, you can sand slightly using a very fine grade of glass paper (be careful not to sand through the tape) or coat with matt medium.