Welcome to Speedsolving.com! I’m new here too.
What helped me the most to get sub-20 (except just practice) was getting rid of my regrips for F2L, slowing down, and getting efficient algorithms for F2L.
I’m Ludvig from Sweden, I started cubing somwhere in august 2018 and I currently average 15-16 seconds on 3x3 (my only event)
but I see great room for improvement and hope on getting NR someday.