What worked for me was a lot of (intentional and natural) variation in line thickness and opacity, and being less stressed about making perfect lines (some lines could be doubled up, have gaps, etc).
Helps make it feel more hand-made and reduce the feeling that everything is flat.
Alt Version - Pt 2 of 2
An AU where Trixie took over Ponyville in season 3 and got a little bit.. addicted to tickling poor Applejack. Days turn into weeks and Twilight is nowhere to be found.
Will AJ Survive her role as assistant? Or become Trixie's permanent tickle pet?