My first attemp at weathering

Better than my first. Now I keep my dirty brush wash, in jars varying from very dirty to almost clean. Their mix of colors, with low pigment count I use to give an "acid rain" look over any colors that appear too clean. Using the different washes and layering the "fill spills" gives the impression of many spills vs one really sloppy one. That said, I would grade yours at "good enough for my house". It looks like the Boraxo is eating its way out too. Keep it up.  

I wanted to look like it had been in use for a long time. I had just let the rust colored paint run down the sides. The same thing with the Talcum powder( Water mix then sprinkled it on and blew off the excess. Than sprayed the whole car with Clear Matte spray paint to seal everything. One side came out better and I forgot to add rust to the roof. Hopefully my next PS2 comes out better.

You can still add to it, never too late. Father time, and Mother Nature lay their messes in layers too. Artists are seldom satisfied, most are their own worst critics too.

It looks good.  I'd leave it as is and not add more weathering.  Most bad weathering examples including some of my early attempts erred on the side of too much: easy to be way too heavy-handed.