Unless otherwise indicated, when you chain 3 to start a row of crochet it is counted as the 1st double crochet of the row. This means you already have a double crochet stitch in the first stitch of the row so you do not need to place another one at the base of the chain 3. You skip the first stitch and begin in the next stitch for your row. This also means when you reach the other end of your project you will need to work into the chain 3 as though it were a double crochet stitch. Sometimes it makes it easier when you are learning to crochet to place a stitch marker in the top of the chain 3 to remind you that you need to work into it when you see it again. If you are working on a crochet project and it is angling off on the sides on a diagonal (or rhombus like shape) it is often because you are missing the chain 3 at the end of the row and/or working an extra stitch in the beginning of the row.
To check out the standard recommended number of turning chains for different stitches please see this chart:
To begin the double crochet stitch, you need to “yarn over” the hook. See the image below for how I always yarn over the hook. Some Crocheters yarn under the hook instead – it will still work but just remember to be consistent in which method you use, as it changes the look of the stitch if you flip back and forth between the way you “yarn over”. Yarn over is often shortened to “YO” in patterns.
Next, insert your hook into the indicated (usually the next) stitch under both loops of the stitch. See below for the hook placement for a regular double crochet stitch. If your pattern calls for you to work in a specific loop you may need to insert the hook in a different spot. You can view this image to understand the different loops of the stitch: Crochet Stitch Anatomy
Next you need to yarn over the hook.
Then pull up 1 loop. You pull the “yarn over” through the stitch. You now have 3 loops on your hook.
Next, you need to yarn over again.
Now you need to pull that last yarn over through 2 of the loops on your hook. You will now have 2 loops remaining on your hook.
Next, yarn over the hook.
Then pull that last yarn over through the remaining 2 loops on the hook. Your double crochet stitch is complete.
How To Make a Double Crochet Stitch
Double Crochet (dc): Yarn over and insert the hook into the specified stitch. Yarn over and pull up 1 loop. You now have 3 loops on your hook. Yarn over and pull through 2 loops. You now have 2 loops on your hook. Yarn over and pull through 2 loops. You have created a double crochet stitch.