That is a good DIY. I personally do it a bit different.
I clean the area well, and go in the scratch with IPA unless I know it is super fresh.
I use a super tiny and fine paintbrush, tough the toothpick idea is good too. I keep a soft microfiber cloth handy.
I fill the scratch well, so it is filled completely. Let it sit for about a minute, then buff with the microfiber. Most of the paint will come off, but some color will be imparted. Repeat.
Layer by layer paint will be added. And I carefully remove it so it stays flat or low.
In the end, after curing, I'll use some scratch x type product to help blend, then after a few days at least, I wax it.