Everything you did was done with a paintbrush and paint from a pot. You'd simply dip your brush in the paint and put it on the model. We all had to start somewhere.
And then you get to feeling good about the results you can get or you see something else that was done with a different tool and you decide to give it go.
This was most likely washes. You're still using the paintbrush, but instead of painting your model with paint, you're using a wash and there are different techniques involved.
And it begins... Now you're 95 percent paint and 5 percent other techniques to get the results you want. And it continues.
Next thing you know, you've picked up using inks or maybe you've started dipping your models to get a certain look. Maybe you spray prime your models now with two colors instead of brushing them with one in order to accentuate highlights.
And it keeps going, next thing you know you're 80/20. You've started using sponges to mimic battle damage. You finish off gems and high gloss elements like blood and guts with a gloss clear coat to make them look real.
It doesn't stop either. Your skills keep expanding and improving. You pick up an airbrush for larger models. You start using weathering powders to get subtle environmental effects. You use things like salt and masking glue to get specific results. You're using graphite pencils to show wear and tear along edges. The list keeps going.
Before you know it, actual painting is a small part of your whole approach to "painting." And that's ok. I didn't realize it was happening to me until I looked at the Howling Griffon model I did a few weeks back. There's not much paint on him in the end. Most of the work is done with other techniques.
The more you do it, the more you learn and the better you get at it. Each time I paint something, I refine a previous technique and try something new. I don't always make huge improvements, but looking back, I can tell I've gotten much better at this "painting" thing.