Designing a good PCB requires some knowledge and good calculator. First one can be obtained gradually by making tons of PCBs and learning from failures. Different thing is calculator. You cannot have all things in mind when tracing crucial traces in your PCB. What is high voltage is present? Or if there are large currents floating. How one or another configuration will behave when high frequency signals are used. There are always a tradeoffs between materials used and price. So measuring things right may save time and cost.
We recommend EasyEDA for circuit design and PCB prototype
Saturn PCB Design Inc. knows these problems and put their experience in a nice free calculator which covers many designing routine calculations. Here you are be able to calculate things like via/trace resistance, capacitance, inductance. By changing inductor width and thickness find its power dissipation. Also you can do quick thermal calculations that will allow to decide if you need a heat-sink. Other things include planar inductor parameter evaluation, spacing between traces on different voltages, crosstalks and more. Units can be selected between imperial and metric. Calculator is refined with many releases and can be downloaded here.