Part-Time judo club in a rented hall

Parents of children (often ages 6 to 14) and adults who want fitness, self-defense skills or competition.

Monthly membership fees, a sign-up fee, grading fees when students test for new belts, and uniform (gi) sales. Tournament trips or seminars can add a little more.

• Solid judo experience and a recognized black belt or instructor rank
• Teaching and managing groups of children
• Clear communication with parents
• Basic organizing and record keeping

• General liability insurance that covers martial arts instruction. Check what your national body membership includes and what the venue requires
• Background checks and abuse-prevention training (such as SafeSport) for coaches who work with minors. Check your national body's rules
• Signed waivers and an injury plan, since judo is a contact sport
• Mats cost money and need storage. Check the venue's rules on setting them up and putting them away
• Check whether your city or state requires a business license, and whether memberships are subject to sales tax in your state

Startup costs are typically around $2,000 to $8,000, depending on mats, insurance and venue requirements. These are estimates, and mats need storage, so check the venue's rules on setting them up and putting them away.

Monthly revenue is typically around $800 to $4,000, depending on how many members join and how often you run classes. Hall rental comes out of that, so work out your costs before you set fees.

Check that your general liability insurance covers martial arts instruction, and what your national body and the venue require. Also check background check and abuse-prevention rules (such as SafeSport) for coaches of minors, waivers, and local business license or sales tax rules.