Cutting Liquid Mask?

[cigbunt]

can any body give me some tips on how to get clean line when cutting mask... what are the "tricks of the trade" to get a super clean cut..

im noob but i've attempted a couple shells.. (will post pics later) they look ok from a distance but when you look closer the lines arnt "super clean"

i put 2 layers on with a brush and leave overnight.. some areas is difficult to cut away.. am i not putting enough on?

also when marking out the shell design do you guys draw 2 lines for an outline or do you just use a thick marker pen..?
after you peel mask do you clean the area you peeled.. if so what with?
if you make a mistake do you use your scaple to cut paint away while it still peels?