You have to start somewhere when you design a quadcopter. We mentioned that you will likely double back on a section of your design. In fact, you will probably double back on every section of your design... more than once.
A great way to start your quadcopter design is by taking inventory of what you desire for your quadcopter. Will it be a racing quadcopter? A filming quadcopter? A quadcopter you just want to somehow release from its earthly tether dagnabit? For our project we considered probably 4 different frame options from more of a racing frame with a protective shell and hollow arms for motor leads (It's called the Skyhero Anakin in case you're super curious now.) to more of a heavy lifting frame with the ability to carry a payload. Making an initial decision now doesn't lock you in. You can circle back later as you get more involved in your desing but an initial direction is a great thing to have. We ended up choosing a 450mm (motor to motor distance) frame that we plan to mount with a camera gimbal during phase 2 of Eve.
Now once you have something in mind, it's time to start making an initial list of all the parts necessary. Here's a list of items to get you started. We know many of you would just end up searching the web anyway like we did so we will try to make this easy.
And finally, though this isn't on the quadcopter itself, don't forget a transmitter compatible with your receiver and a battery charger compatible with your battery.
Now that you have your parts list, let's move on to the next step: Initial Weight Calculation.