Can you do it well?

I'm absolutely awful at lying. I think it may have something to do with just not wanting to be dishonest.
I'm not sure if this is a good thing or not.

If im asked a direct question, and I've been naughty (god I sound like im 5!) my face just goes all red and I give it away by biting my lip,cringing a bit and twisting my feet. For instance the first time my step dad busted me for having skunk; I was in my mums room, on her bed and we were having a good chat, then Sean comes in and says there's an odd smell coming from my room "Do you have anything you shouldn't in there Sophia?"
Me- "No......erm *looks ridiculously guilty* *sighs* yes"

I just CANT lie about things like that.

I dont know how well I am at spotting when other people are lying. My big sister is a massive tease so she's skilled in the art of lying. But with my little sister I know like that *snaps fingersif she isn't telling me the truth.
I can also always tell when my best friend is lying, I think just because I've known her for so many years and know her so well.

Anyway enough of me rambling.
Can you lie well?
Do you feel guilty when you lie?
Told any WHOOPERS?