h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

To view the sun, project through a small telescope*, NEVER EVER look at the sun through the telescope, onto white card. Again NEVER EVER look at the sun through the telescope.
This is an effective way of getting a focused image which is larger than you would get with the pinhole method but remember NEVER EVER look at the sun through the telescope. To do this, point the objective (the lens nearest the object) at the sun and hold the card near the eyepeice (the lens nearest your eye, if you were using the telescope normally). You'll need to move the telescope and card to get an image NEVER EVER look at the sun through the telescope to find where it is. Once you've got the image of the projected sun on the card, you can focus the telescope to get the projection in focus.
Always remember NEVER EVER look at the sun through the telescope.

*This method is probably easiest with a refracting telescope (the sort with a couple of lenses and a long tube to look through). You probably could use a reflecting telescope, but finding your image would probably be harder.

Always remember NEVER EVER look at the sun through the telescope.
Is that enough warnings?

This method has been used by astronomers to view the sun for a long time and during the August 1999 eclipse I saw someone using this very method with a crisp clear image of the sun projected onto a card.