I guess my biggest takeaway was to use proper scribing guide tape. I initialy tried using tamiya masking tape stacked two or three layers thick like I saw in some tutorial videos but I tended to push the scriber too hard against the tape and it either got pushed in, leaving a divot, or I pulled the scriber over the tape. I didn't even consider trying free hand.
With the plastic guide tape I could push much harder against the tape with no fear of deforming it or pulling the scriber over it. The tape did slip a bit with the pushing, especially for short lines where there was very little surface area under the tape but just holding it down with my thumb kept it in place just fine.
I also found that for curved surfaces, it's better to pull the scriber up the plastic, like walking up a hill, rather than pulling it down. Gravity helps keep the scriber on the plastic and gives more control. The other way risks pulling the scriber away from the plastic and going off course.
Overall it went smoother than I expected. The end result isn't perfect but I'm more than happy for a first attempt.