Whatever disputes you had with your former manager or workmates, a job interview is definitely not the place to air them. Apart from the possibility that your interviewer also hates your ex-boss (which, let's be honest, is slim), your grievances are only like to result in "trouble" being written on your notes. Instead, attempt to put a positive spin on your disagreements or at least present them in a constructive manner.
Claim to be faultless
Don't go into a job interview and immediately launch into all of your faults, but equally make sure you've got a good answer in place when you're asked what your biggest weakness is. This question pops up frequently in interviews, so prepare an answer that makes you seem honest, but still highly employable. If you're really stuck then try mentioning something that would have little impact on how you perform your role, or point to a previous work challenge that you successfully overcame.
Leave your phone on
Even if you don't answer your phone during the interview, the slightest hint of a ringtone will instantly affect your job chances. It comes down to attention to detail - if you can't remember to even put your phone on silent during a job interview, then what else might you forget? Having said this, it's always worth bringing your mobile to an interview in case you run into any problems on your way in. Which brings us to...
Turning up late to a job interview is a guaranteed way to annoy your future boss. But if you're running late, then make sure you phone ahead and let them know with as much notice as you can. You're still going to need a very good excuse though, so take all precautions to make sure you can arrive on time.
Perhaps the most important part of a successful interview is to do your research beforehand. Find out as much about the company as you can - what do they do? Who are their customers / competitors? Etc. Employers often ask interviewers what they know about their company, so make sure you've got more to offer than an awkward silence.
Show that you're tired
It's understandable to have trouble sleeping on the night before a job interview due to nerves, but don't let it show. You've only got to be alert for a few minutes, so focus and maybe get some caffeine. One of the main attributes that many employers look for is enthusiasm, so make sure you don't come across as unfocused or uninterested.
The only time it's ever justifiable to wear causal clothes to an interview, is if you've been explicitly told to do so. For any other occasion, it's always far more sensible to dress smartly. Even if companies have a casual dress code for current staff members, that doesn't mean that they want potential employees to turn up in t-shirts and jeans. Iron your suit, have a shave and make the effort - you'll be annoyed if you've lost the job because of what you picked out of the wardrobe.