Layout of Instructions (Outside)
The first thing you need to do is to flip your pattern to the back. Your back has a list of things you need to know before you start sewing and your shopping list.
I went to Simplicity patterns and picked a costume for Jedi garb and cloaks for this example. and will tell you about each people of the information.
Side
If you look on the side there are some images of the clothing. Some patterns will only show you the backside of the pattern, since the front will have the front parts, or they could have both front and back views. This allows you to see details in the costume. It also gives a letter to the costume. This is important for figuring out which piece you want to do. Often costume sets are labeled the same letter, but that is okay. I'll tell you more about individual pieces as we talk about the rest of the packet.
Top to Bottom
The rest of the instructions starts with a brief example of what is in the packet. In the case of this pattern it says "Misses', men's, teen's robe and tunic". This can also give you clues to if it's a historical pattern and what era.
Your next section talks about fabric and switch fabric to use for the costume or for parts of the costume. The fabric guide is just fabrics that they recommend, but not require. The recommended fabric looks better in the way it folds.
After that it's notions. Notions are non-fabric pieces (like buttons and hooks) to help complete the garment. The packet in this spot will tell you what and how much you need for the piece.
Measurements are next. It's important that you get the right size. To do this you measure the suggested area. Some areas you want it tight around and some areas you want to make sure you have breathing room. Think of it this way tight and straight, breathing room and circular. Always take the size with the largest measurement. Once you learn more you can adjust the sizing for it, but you don't want to make it too small.
Now comes the fabric amounts. You find the amount of fabric based on your measurements. Each fabric amount is in yard intervals. So when a size XL robe A calls for 8 3/8 it's saying it needs 8 and 3/8 yard. I also recommend (as do others) getting a little extra fabric just in case you have a mess up. You'll notice that there are instructions for how much fabric an individual piece has, this allows you to make that one piece.
Here's some videos to help out
Patterns by Cosplay FabricsHow to read and envolope by Koumori no Hime
