If you have the basics of drawing and are under pressure on costs, you can try to do it yourself. You need to study the relevant parts of the Patent Examination Guidelines and understand the requirements for patent drawings. However, there is also the issue of content writing for patents, and there are also very skillful people. If you can't figure it out, it's better to spend some money and hire a professional to do it. Gradually you get to know it, and if you think it works, try it yourself.