I find answering who, what, when, where, and why generally puts me on the right path. It may seem trivial but going through the process of answering these questions will determine the design and quality of the work required for the final product. It will also help with what tools are required.
Why is always first and will be asked throughout the process.
That leads to the design stage. During the design stage ask the "what" question. What will this be used for, fileting fish or chopping wood. What are the design characteristics specific to the task. Draw it out with whatever tools your comfortable using be it pencil and paper or CAD.
Who will be wielding this tool? Male, female big hands or small, perfectionist, pragmatist, or utilitarian. Please keep in mind this is all high level q & a before ever wielding a hammer or putting steel to grinder or file. Go back and tweak your design.
After the design stage, what tools are required to achieve the vision? This then leads to the "where", which is obvious, and "how" which leads to technique. Go back and tweak your design to again fit these new parameters.
After all those questions are answered and the tools are in place, your ready to research the art of the techniques required to fulfill the vision. Go back and tweak your design again. You now have a plan. Execute it, poorly at first, but better over time.
Just my 2c on where to start but its the process I went through.