My preferred way is to use a leather silver marker around the template, then with the template removed, follow the line with a round awl, then either use a round knife, or for lots of curves, I use a small Stanley knife. Doing it this way allows me to tweak patterns a little bit for a bit of personalisation for each item, but it also stops me getting into a bit of a rush,, and so not wander off the line.
I also think that it’s important to make sure that whatever knife you choose, it fits comfortably in your hand. It’s way easier to follow the curves if you have full control of the knife, and it’s proper sharp. Stanley knife blades are disposable for a reason, and starting out with a few minutes stropping my round knife is quite relaxing.