While on a date if you are confused just ask. The first time I had sex I wasn't sure if she was interested in me so I just asked if she wanted to have sex seeing as I'd never had it before (at least willingly) To ny suprise she grinned and well I'm sure you can imagine the rest.
I've never been good with job interviews. As you can imagine it doesn't help when they go to shake you hand and you step back looking like you are ready to kill them if they touch you.
We all make mistakes usually the same ones over and over. Try not to beat yourself up, instead if something doesn't work try something different. Also there is one good thing you found Psychcentral forums