No offense, but your first suggestion about sutting and pasting sucks. The second is better and the third is close to what I use and is probably the most used way
Either way, you need a photo editing program. Photoshop = expensive, Gimp = free.
From another thread, regarding how to do it in PS:
UMMM WAY TO HARD!!!!!
1.) Buy photoshop (elements or CS3 will both work for this)
2.) Import your pictures.
3.) Select a Picture. Click on Layers (On the top bar of your program)
4.) Select (Duplicate layer)
5.) Rename your layer as B&W (so you don't get confused of which layer is which.
6.) Click "ok"
7.) Hold down the apple key and press the letter "U" this will give you the saturation option. (There is a shortcut to make the picture black and white, but I forgot what it is.) On the saturation bar, bring the arrow all the way to the left. This will cause the top layer to be Black and White.
8.) Select the eraser. At the top of your program you will see a couple of options. Eraser size and Opacity level. Set the opacity level to 100% and teh eraser size to your preference. (By not setting the opacity level to a 100% you will have what appears to be a black outline around whatever you erase.)
9.) Erase any part of your black and white picture, and the color from the bottom layer will show through.
10.) When you are done click on "layers" again and select "flatten layers" Now save your file and Voila you got a great lookin picture like everyone else.
NOTE: If you would like to do a little bit of desaturation and etc than it is better to do it on the original picture. It makes it quite a bit easier than adding extra steps. AND ALWAYS KEEP AN ORIGINAL COPY OF YOUR PICTURE!!!