I used to use the edge of the brush too which worked really well. I recently tried using a white gel pen (Uniball Signo about £2.50 from ebay) and I have not looked back, much easier.
Aye my first effort below.
I thought it was perhaps somewhat OTT, but might be worth considering. Another thought has since occurred to me, but at least until such time as I have personal experience to go by, I'll keep it to myself.
Sure but I'd like to make it quicker after all.
Got the paint pen and charged at a black hat with it...
I took two coats...
and is a bit cocked, purely me and a first approach, ikely to get tidier with practice.
but then tidied up by blacking in as RobH suggested and I'm happy with it...