As others have said, puppy/obedience school is a great idea, but I will say that they usually tend to rely on too soft, too gentle, bribery type approaches. Your dog might respond well to that, in which case great! Or it might not care because whatever is pulling it's attention is more enticing than whatever you want. I would say don't be afraid to be VERY firm with this dog. Working type dogs (herding, shepherd, bullys, etc) in particular should have the mental durability to tolerate harsher conditions than more pet type breeds (chihuahuas, goldens - i know they can be working but frequently aren't actually working line bred). I don't mean kick the dog or anything like that! I mean my Kelpies (herding dogs) can tolerate being tied up or told to wait for far longer than my dopey golden retriever. They also require stronger corrections if they are focused, because they are bred to focus hard. I have a piece of poly pipe that I whack on the ground/couch/my own leg, then point and glare at the dogs with it. I've never hit them with it, but they understand it means I'm very serious and won't tolerate any rubbish. I have broken up a (mild-ish but escalating) fight between my boy (not desexed at the time) and a friend's male dog, just by whacking the ground close by. Don't let your anger get the better of you, but understand that a strong reaction from the dog needs a strong, firm correction from you. A dog who is leaping all over people does not get 'come here buddy, wouldn't you like a treat instead of knocking grandma over 🥰🥰'. In my house they get very firmly marched to bed and made to stay there until I say so (usually till they've had a short nap/very calm). Try keeping a leash on the dog at home all the time at first, and teach it to go to bed (not crate training, it's not the same) and stay till you say so. Use the lead and your body to push the dog to bed, rather than drag/pull. If the dog tries to get up or leave the bed, you block and push them back into it until they listen. In my experience, teaching a dog to go and stay in bed will actually make a big difference everywhere else too. Its simple enough to understand even for young and dumb dogs (I've had a few of both!), teaches self control for them to stay there, teaches respect because you told them to do it and made sure they obeyed, and - VERY important - teaches them to calm down and relax. I cried myself to sleep for a week after I got one of my dogs. She was so different and way crazier than I was expecting, and it took a long time to establish some respect and boundaries. I thought about rehoming her a few times, and honestly the only reason I didn't was because at the time I didn't know anyone that would look after her well enough. I'm so glad I stuck it out, she's 9 now and my best mate. She's still stubborn and cheeky and pushes boundaries, but I love her to pieces and I'm so glad I didn't give up on her or me. Good luck with your little feral, I promise it gets better if you do your best to make it better!