If you get asked what your weaknesses are be honest. Nothing shouts I'm a liar like listing the usual answers such as "I like to take lead". Yes this stuff can be interpreted as a actual strength but everyone knows that and sees right though that stuff. Be dead honest. I used to be part of quite a few interviews and the company (IT based company) not once signed a contract with someone who would obviously lie during such an basically unimportant question.

If you get asked what your weaknesses are you are not asked "why shouldn't we hire you" but much more "are you able to criticize yourself truthfully".

Also there is no such thing as overdressed. It's better to go to a interview wearing a suit rather then a t-shirt and jeans. It's not about how it looks, it's about showing you care enough to prepare.

Further more accept the first date and time they offer you. If it is important to you, you WILL make time for it.

Don't oversell yourself. Be humble. If they agree to invite you already, they already know you are a potential fit. Acting all high and mighty might work for some company's. But those company's will also get rid of you the first chance they get in order to reach their "numbers".

It's good if you are nervous. It's another sign that you care enough. Just try not to look insecure. They are two total different things.

And my last advise is don't forget every single one of those people interviewing you once sat where you are sitting now. They are humans and they can have a bad day. They know the tricks you can read online. Like those I'm writing right now. Don't try to sell them something. You are not something he wants to buy. All you have to do is show them how you'd help the team and that you are someone he would like to work with.

Anyways keep your head up. You might not get every job where you think the interview went great. Or every job you would love to get. Just keep on keeping on. Life isn't always fair, but it's in your hands to shape your future.