For me, the breakthrough was getting a thermostat controlled soldering iron. Suddenly I could make perfect joints every time.
You can solder on 0805 parts and switch to soldering bolts onto nuts without changing the tip or any settings.
If you have the power without the thermostat, you will reach unsafe temperatures and burn what you're not supposed to burn.
PID controllers make a huge difference.
It’s actually much harder to make a good solder joint with lead free solder, so be kind to yourself about it. No harm in re-doing a joint.
Anyhow, I never fried a part with the iron. Heated the wire just enough to flow the solder, and applied heat only barely long enough.
To avoid needing a third hand for some joints, I'd pre-fill the hole with solder. Then heat it up again till it melted, and push the wire in.
Once I switched to Kester solder, I had a much better more consistent experience. My hypothesis is that cheaper solder doesn't have the flux as evenly distributed, so you get spans of solder with too little flux and then everything gets worse, then you hit a good patch and it gets better.
P.S. I worked my way through college being an electronics assembly technician, so I spent a lot of time soldering. I enjoyed making the boards look perfect.
It turns out, this skill is transferable to soldering copper water pipes. Never had a leak! (Using a torch not an iron.)
I didn't go lead-free because I've heard leaded solder is easier to use (lower melting point?) and since I'm just a part-time hobbyist, the health and environment considerations are minimal. It's not like I'm soldering eight hours a day every day.
IMHO...despite the risks of lead...leaded solder is way easier to use and especially inspect. Lead free often looks "cold" just by the color of it.
Use a larger tip for higher heat transfer. Don't increase temp...this is how people burn boards and lift pads.