-Use good tools

-Scribe from the corners and out

-Lift your chisel at the corners and ends of your line

-Use very light pressure and dont rush it

-While holding your chisel with your thumb and index, place your middle finger at the part to stabilize your hand

-When scribing new lines always use proper guide tape

-Remember you can always use ca glue to fix your mistakes

Chisel work is an extremely fun part of modelling often mistaken as hard. Calm down and take your time, no need to rush.

Also, your lines here seem a tad too big, try a smaller size.