How much more detail do you want from a tutorial? That one looks pretty thorough to me. It's very simple and straightforward. You can use paper but I prefer cardstock since it's a firmer medium to cut around. Get your picture and cut out the components. I size my picture in Microsoft Word to make sure it will fit on the cake. I do mine a little differently than the tutorial. Instead of building a base and putting all the pieces on that, I cut out each individual piece and then kind of put it together on the cake. So using Ariel as an example, I would have cut the head, torso, and arms as one piece, using flesh toned fondant, and then cut the purple shell bra and attached it using water. I would have cut the fins out of lighter green fondant and then the tail from the darker green. I suppose it's easier to have a base to put everything on, but I have always just done it separately. Making a base has its advantages though. You can easily move pieces around and reposition and stretch them without marring the buttercream. Maybe I will start doing it that way.
The key is to make sure you roll your fondant thin and let it dry so you can cut it cleanly with a sharp knife. Otherwise it will tear and stretch. Sometimes I roll mine out the night before I'm going to cut it and then put it on a plate covered in plastic wrap so it doesn't get rock hard.
If you want, I can try to make a tutorial this week since I have a cake on Wednesday. It's simple though-just a turtle.