Finally got my first invite to the job interview

wear a silly hat, it will make you look unique

If you have a friend that is good at dealing with people and has the time to help you. Check out some common questions used on interviews on the internet and ask him/her to make those questions to you and later tell how well you were at them. Practice for some time just to get using to the kind of questions commonly used.

Try to be focus during the interview and gather what they might be looking for as a person apart from the job position itself from their questions and try to make yourself fit into that role, but dont wander too far off into that "ideal person" that it's not who you are.
Dont be afraid to show your own personality as well for good measure but not too much till they can read you like an open book.
Remember to prep up yourself the day before to make yourself feel your best or in other words comfortable for the interview day.

As a person who has weak nerves at times, I always picture the worst possible scenario in my head a lot of times and try to scare myself until I form up a plan on how I can overcome it (in my head ofcourse). And usually reality isnt as bad as how my imagination pictured the possible scenarios, so alls well ends well (But this method works for me but im not so sure if itll work just as well as anyone else so be aware!).

Lastly good luck mate and if somehow you didnt get it, dont be down, avoid that by looking at what could possibly be the reason you didnt get it and always learn and grow from it.

Haven't had much experience, but from me.

Present yourself nicely.
Think about what you say.
Be confident, and don't show any nervousness. That's 1 thing the employer/manager will look for.
Stick with positive things, to say about yourself. Don't mention a negative.
Don't fidget with anything. Always keep your eyes to the employer/manager. (For me, this was a bit difficult, since I can't look at someone for too long).

And I guess, just be honest.

Before your interview, you could always research about the company, and some interview questions.

working sucks :( except the payday and fridays :p

Stay optimistic :) no one likes a grumpy face.

Good luck on your interview! I would definitely suggest coming up with some good and relevant questions to ask at the end of the interview.

If they ask if you have any questions, ALWAYS ask some. Whether its what kind of people youll work with, or what will be daily expectations of you, if you ask questions theyll be more impressed and will assume you are more interested in the job than those who dont ask questions. Good luck!

pro tip: keep eye contact and don't look like you are scared. Good luck