First up congrats on your new airbrush purchase
Also congrats on having a question other than; what airbrush should I buy?
Using the airbrush is a bit of a learning curve, I suggest you start getting used to it on some scrap paper or models you arent bothered about
Some other basic things your going to want are;
Cleaner solution - this could be windex (car window cleaner NOT household), store bought airbrush cleaner, denatured alcohol, acetone etc etc
Thinner (or prethinned paints) - this ones wide open theres a lot of debate on whats best.
For me I like Vallejo Airbrush Thinner, or Liquitex Airbrush Medium. Both work great with citadel paints.
Premixed paints, Vallejo Model Air are very nice paints indeed, worth buying for colours your going to use a lot. I got the 16 colour basic set and plan to grab lots more of them)
Some pots/cups to mix in - disposable plastic shot glasses work well.
A stand for the airbrush -

when its got paint in, you cant put it down without it spilling
lol. These are often built into cleaning stations
Cleaning station - this is handy for spraying out the contents of the cup when cleaning it out, its a little pot with a hole in for you to put the nozzle in and spray so you arent getting it all over the place.
For starting out it might be easier to go with premixed paints, as it can be a headache getting it right to start out.
But for thinning your existing paints you want to mix it up in a separate pot using an old brush or something similar, and then pour it into the airbrush. Aim to half fill the paint well at the most, you will probably be surprised how far it goes when you get the thinning right.
Thickness... your aiming for skimmed milk.. which is rather subjective, find youtube vids on thinning paints for airbrushing to see what we mean, trying premixed paints first up can give you a hint as to what your aiming for.
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lol I've rambled a fair bit probably covered nothing useful
lol, if youve got questions post them here someone will probably post something pretty quickly.