Spraying is a good, cheap, short-term alternative to airbrushing. Although you can't adjust the airflow, paint color or the amount of paint released, it can give good results overall if used right. You can probably find mainstream spray can brands like tamiya in any hobby shop too.

From my experience, these don't really require primers if you clean the parts thoroughly to get oil and dirt off before you spray.

Before you spray, you should always remember to shake the can so that the concentration of substances within the liquid is constant. The metal bearing inside the can should stir the liquid inside furiously as if you yourself were doing it with a stick.

When you're spraying, the distance between the object and the spray can nozzle should be about 30cm. Spraying too close can result in dripping paint and spraying from too far will allow the paint to blow away or become dry too quickly. Try to apply the paint in one continuous session as it will leave a constant, even coating.

Spray paint should be rendered on the object by gradual coatings. If you try to paint it all in one go, the object will end up with dripping paint, which will take much longer to dry and will leave the drip marks after it's dried.

Remember to wear safety equipment such as proper filtering masks and safety goggles.