Here are two ways to draw a turtle. The first one shows how to draw a turtle as if you were looking down on it, and the other shows how to draw a turtle as if you were looking at it from the side.
Both of these can be done by young children or by adults who are not confident in their drawing skills.
Just take a deep breath, and do at least three drawings following the instructions. Almost all of my first attempts at drawing something turn out awful, but usually by the third try (and sometimes by the fifth or sixth try) I do something that really surprises me.
How to draw a turtle - overhead view
Draw an oval. This will be the shell of the turtle.
Draw the head and the tail. The head can be round if you want, but most turtles do have angles where their eyes are if you look at them from above, and their noses come to a point.
Draw the feet. I think of them as little paddles.
Draw another oval inside the other one. This seems to make the shell look a lot better, and real turtles have this rim around the edges of their shells.
Add the eyes. They can be little dots, or you can just suggest eyes by making the segment of line where the eyes would be just a little bit thicker.
This is the hardest part of this tutorial. You can skip it if you want - people will definitely still knowyour drawing is a turtle, but it is actually not that hard to make. Start at the front, near the turtle's head. See those two lines of the turtle's head, and where they attach to the shell? Now, see the first half of the kind of diamond shape that runs down the center of the shell? Start there. Make the half diamond shape (actually it is six-sided, so its a... hexagon! I'm sure you guessed that) first, in a row along the center of the turtle's back. Then just connect the other lines to the inner oval that you drew just before. Not so hard, eh?
Add little claws at the end of the feet. This is optional, too, but I like the way it looks, and it makes the drawing look just a little bit more realistic.
Step 1) Make a shape that looks like this - kind of like a hat.
Step 2) Draw the turtle's head.
Step 3) Add the front foot.
Step 4) Add the belly, the back foot and the tail. Make a little dot to represent the turtle's eye.
Box turtle If you want to draw a box turtle, make the shell rounded and high, almost like a half circle.
Slider or painted turtle If you want to draw a painted turtle or a slider, make the shell lower. Painted turtles' shells don't arc up as high as box turtles' do.
Snapping turtle To make a snapping turtle, make the nose have a really hard angle, almost a 90 degree angle. Also make the top part of the turtle's mouth into a hook. Don't add teeth, though. Snapping turtles don't have them - they've only got that big "beak", but its more than enough to be dangerous.