If you want to be successful, you need to take some of those courses that are available online. You may have to part with some more cash so as to access the course, but it is totally worth it, especially when you want to make some money from the drone.
There is a wide array of power cable accessories available in the market and if one has to name a few of them then heat shrink tubing, PVC caps, insulation tape, inline transition joints etc get included in the list. However, while choosing the right set of accessories, it is wiser to follow the checklist given below Voltage: Buy an accessory whose voltage is similar to that of your application.