I have been running my own businesses since high school. Part time business and part time jobs. Now I'm full time business owner. It's the best thing I've ever done. ISTPs should be business owners. Or like this: ISTPs should be independent and in control of ourselves. Not all businesses will appeal to you. Some you will never want to do. Retail store with shelves where customers can shoplift will drive you crazy. Do something where people can't steal your stuff. Where your product is too big to steal (furniture) or out of reach (food in a restaurant kitchen) or only you have it (contractor tools)
The trick is to filter out businesses that let you be comfortable, which to me means limited interactions with people, i do things on my time, limited paperwork, I like to do something a little mechanical, since I'm mechanically inclined, be busy enough for it not to be boring, but not too busy for long hours dealing with people, its very important not to be in customer service too much because very soon people complaining will get on your nerves and you will not feel in control and get irritated.
Pick simple businesses. One person businesses are best. Like self employed contractors, small fast food take out joints, catering, car mechanics, massage therapists, makeup artist/spa, tattoo artist, sign business, driving instructors, couriers, truck drivers, flower shop, landscaping, tailor, cleaning company etc. I started fixing up and selling cars, sold on eBay, still have a hot dog cart, and now I own a laundromat, i fix washers. Hot dog cart is for short hours, deal with people for 3-4 hours, so after lunch you don't have to deal with people anymore. In a laundromat there is nothing to steal. People do it themselves. I have a change machine, so I can go out to do errands anytime. I like occasionally fixing the machines.
These businesses have minimum paperwork, simple inventory and are flexible so you have a little bit of freedom. Nobody breaths down your neck. But you have to be ambitious and accept that you will have to be there and sometimes dedicate long hours to it. It's not 9-5. If you're lazy, you won't make money.
But don't get partners. You will need to hire people for certain things, but never do partners where they have the power to make decision about your business with out your approval. Partnerships have a very low rate of success. Why? Because you can't have two bosses. There has to be one person on top who makes the final decision. And that's you. If you need money, have a silent investor who cannot make decisions about your business. They get a percentage on their investment. They are investing in you, not the business. But if you screw up, they still have to get paid. Just like getting a bank loan.
Figure out what you like to do or better said what you don't mind doing. Start small. Start part time to get the feel of it. Maybe get a job in one of these businesses, learn how they do it, then start your own. It's worth it.
