I'll still help almost anyone if they ask, the only thing I'm really cautious about now is gas or gas money, and also lending my phone to anyone. I remember one time a guy asked for $20 for his Dodge Durango for gas to get to some city not that far and I had no cash on me, told him as such, and I told him I'd pump him $10. My bank account was double digits at the time and I wasn't doing spectacular for money either. I did it, and he was pretty ungrateful and kinda pissed at me. Since then I've not helped anyone else with gas. If I'm driving or walking somewhere and it's not too inconvenient and I have cash I'll give a few $1s to a homeless dude, I've had some just say "Hey I need $2 for a beer" and I kinda prefer that honesty. One person with gas about 5 years ago in a parking lot I felt bad about, as he seemed legitimate and I could have helped him. Told me he had a job at ____ and his car ran out of gas on the highway, and he offered to pay me back if I helped. I could have helped him, but it would have required me taking him in my car to my house to get gas cans, and driving him to his car, he didn't really seem dangerous, it just would have taken an hour or two out of my day and I just felt more calloused about helping people at that time, and it happened after ungrateful possible scammer. I still feel kind of bad about it for some reason.
For phones, another time I've been burned by a woman asking to borrow my phone at a hotel in Florida, and then later I saw her on a phone on her balcony. I get a call from some gangster sounding dudes, and I saw her go into a car with them later. Turns out she just borrowed phones to call her drug dealers in case one side or the other was wiretapped.
One thing I'm big on trying to help is giving people pushes, especially if they're in a dangerous location at a stop sign or something creating a traffic jam. I view it more like I'm helping everyone around me avoid an accident or traffic blockage. I try to always push them to somewhere safer where they're not blocking traffic. One person I helped in a fairly busy city intersection had nobody stop to help him for an hour and a half stuck at a light, even the police did absolutely nothing to help, and there was a gas station on a right at the light where I pushed him to for safety (it was a 90s Honda Accord, pretty light, and the owner got out and helped, too.)
With karma and all that, it's also the golden rule of do unto others. I can't say by any means I'm some sort of great upstanding extremely moral person, but I've been helped with jumps, I've been helped by pushing my car before, helped in all sorts of ways by complete strangers over the years. So I feel it's important to pay it forward if I can.