OK here are some of the techniques I use to scribe the parts off the sheets, so please bare with me:
First I just want to let everyone know I have no workspace where I work, no desk no fancy work booth, I work were I feel more comfortable, and that's working in my chair in my living room, I have a portable computer table I got from Stables that I work on and it works.
Anyway the first thing I do is make sure the part i want to scribe is firmly flat and held securely down on the table, I always start from the top to bottom of the scribe line that way I can the stroke straight.

I follow the part down and scribe about three or four times to start until I can feel that the scriber is cutting through the plastic.

Once I know the cut is almost through the plastic (turn the sheet over and you should see a white line where you scribed). I use a #11 xacto cutting blade to start cutting and remove the part from the parts sheets.

I use a #11 xacto cutting blade because it a little flexible and follow the line where I scribed to remove the part from the sheet. If you miss the scribe line no worries just tweak the blade a line until your back on track.

Now if you total cut into the parts while cutting it off the sheets no worries here also I will show how to fix these mistakes.
So I hope you like so far and enjoy.
Mike