HVAC <-- one of the best.
Bodyshop work <-- alot of fun and fulfilling. can easily learn vinyl car wrapping, and other things rerlated to cars and customization
Electrician <-- another one easy to get into
Phlebotomist <--- if you're okay with clinic/hospital settings and drawing blood
Xray Tech <-- another one , forgot the name for it
There are others but probably not as fruitful. HVAC you can make alot of money quickly.
A big one these days is selling Solar to homes, businesses.. which can be widely fruitful but its a sales job. You can always sell insurance which has a never ending demand.. but thats another boring gig. Real estate is good but if you already have a business saavy, go getter mindset.. In Real estate, you have to be a big self starter. if you want to get into it, get into Real Estate Wholesaling. Most fruitful and least barrier of entry.
Me personally, I got into Ecommerce 5 years back after owning a graphic design firm for about a decade.. I was a self taught graphic design artist , then tried my hand at business, first t shirts, reselling furniture, electronics,you name it.. always been a hustler.
E commerce blew up for me and lets just say I'm more financially secure and more independant than ever before. I'm not filthy rich or anything but I'm doing extremely well for myself.
What's ECommerce? -- Sourcing and selling products online , then marketing and managing the business. Marketing usually happens thoruhg advertising platforms, mostly Facebook, Google, Instagram, but also TikTok and Pinterest .. Other avenues too but these are some of the most popular ones. I've spent so much money in advertising from my start and on failed attempts/stores that did not become profitable enough for me to continue.. (didnt have a good ROAS (Retrn on Ad spend)... to then finding success, and then spending more money on advertisements than I've spent on alot of things in life.. Advertising is the lifeblood of ecommerce though.. its how u keep the train going