No matter how big or small every company (even a sole proprietor) needs a logo to establish an identity for their business. If you have some creative skills you can offer logo design as a service.
You will need a portfolio to show people examples of your work. Design logos for friends and family for free starting out just get build up a portfolio to show potential clients. You can also start out on Fiverr and design logos for $5 starting out (you will get $4 for every logo designed), you can start out charging more if your work is excellent. It goes without saying that all logos should be designed as vector graphics so they can easily be scaled up or down for whatever purpose from billboard to postage stamp size and retain its quality.
How much to charge
Depending on your creative abilities which will guide how much you can charge for a logo. That being said there is also whether you should charge per logo or per hour. Some designers prefer to charge per hour as some are pedantic and can’t make up their minds. But you can still charge a fixed fee and say 3 revisions. And anything above three revisions will be extra.
Design software (Inkscape is a free vector graphic editor)