When starting to design a rocket, sit down and plan out your ideas. Think about these things:
What type of engine do I want to use?
How long should the body tube be?
Which recovery system is appropriate for the design I'm thinking about?
How big do the fins need to be? What shape should they be?
What parts am I going to need to build this?
Next, draw out your plans. The picture dosen't have to be perfect, just a brief sketch. From these plans, you can then go directly and build your rocket, or draw them to scale, labeling the measurements.
