I've deigned and shipped a lot of custom retro script snapbacks at this point. Different sports teams, different companies, barbershops, all kinds of requests.
And if there's one thing that stands out to me, it's this. Simple design wins...every god damn time.
Example. People sometimes come to me wanting five thread colours, a two tone hat, every word a different colour. Hell nah.
Perhaps it's the thought that more customization feels like more value. But believe me, 100% (strong conviction I know) of the time it does not look as good as you'd think.
The retro scripts that actually turn out best, are the clean and simple ones.
One or two colours . Clean and subtle contrast. Just let the green underbrim and the classic shape do the talking.
Honestly it's like most design stuff. Less is more, even when it feels like it shouldn't be.
If you're designing your custom retro script cap with El Cappo, here's my advice.
Pick a colour for the main retro script text - and then match the outline colour (if you have one) with the top text colour. Not that you can't make the top text the same as the retro script, but it's a good rule of thumb.
All in all though, just limit the colours in general.
A good example is a black cap, with all white text. Seems boring to some, but it's an absolute CLASSIC to those that know...
Trust the classic look. It's classic for a reason.