Looking with my eyes

Looking for a job is pretty stressful, especially when you can't find one, but you desperatly need one to do your next shopping. I have an interview lined up, but last time i went there i blew it for some reason. What should i do instead? I thought that was nearly the best interview i had given. I'm just so not used to interviews. When i started work at Swanland News there was no interview, i was a paperboy before that so i just got the job, then when i worked at Swanland Conveiance Store, it was a case of the manager coming up to me and saying "Do you want a job?" the next day i was training. Then when i worked at BHS, it was a group interview, which i aced, along with Fiona, though i wasn't there long before i quit (about 2 months). Then there was Subway, where i really didn't want to work at all from the start, but i thought i'd give it a go. Oh how wrong i was for giving it a go - i lasted 3 working days.
So i've only had 50% success rate since i've been in Northampton with interviews that is. But still i'm thinking that maybe i'm just not good at interviews at all.

So what should i act like? Out there, or just normal? This time i'll dress better for Vue though cos last time i went in my cream trainers - maybe that was why? Well i didn't have any work shoes back then, so what was i supposed to do? I also tend to ace interviews better when it is a woman interviewing me too. I've only had one male interview me - and that's the one i didn't get.