What you need to get started !

1. Spray paint cans – there are many places to buy spray cans and to start with you’ll need a selection of different colours, to give you options in your paintings. This is the most expensive cost to start with as even though individual cans only cost and few pounds, the amount you need adds up the total.

Try to start with at least a dozen cans to include the obvious colours red, blue, yellow, green, orange, pink, purple and silver. Get two blacks and whites as these are much used colours in most paintings.

If you can afford it, try to double up on these colours (24), getting light and dark shades of each colour and doubling up on the black. If you’ve got a soft spot for space scenes your black will soon run out.

There are various brands, so choosing one is a personal choice, but most painters opt for gloss finishes.
2. Caps – usually new cans arrive with caps included, but not always. There are tons of different cap types, including fats, skinnys, ultra skinnys, soft and stencil caps. The list is endless with some caps producing thin consistent lines while others have a more scattergun effect.

Some caps continue to emit paint even after you’ve released your finger and others have dual functions. The best idea is to order a selection at the start and see which you prefer.

3. Posterboard – the medium of choice on which to make your masterpiece. Posterboard is a cross between paper and card and has a gloss finish. Some posterboard supplies have double-sided gloss finishes, which is useful if you make a mistake and want to start again without wasting paper.
4. Tools – to make patterns and create templates you’ll need a craft knife, palette knife and any other type of blade that you can wield to create patterns in the paint.

A straight edge is a builders’ tool that you can utilise to spray straight lines and retain your spray in certain areas of the picture without affecting other parts. These are usually around 18 inches in length. Any straight tool with a definite edge will suffice.

5. Protective wear – spray paint emits harmful fumes and you don’t want to breathe this in, so a mask is a must, especially if you’ll be working indoors. Decent respirators are made by 3M and can be bought online. You can also buy refill filters for the mask and these are much better than the cheap throwaway masks.

Latex gloves will protect your hands from the paint which in large enough quantities can also get into your skin. These can be bought in disposable packs and are very cheap.

6. Newspaper or magazine sheets – freebies! Just take any old newspaper or magazine and rip the pages away from the spine and hey presto, you’ve got your texture makers.

Pieces of card will be useful for making templates with your craft knife and things such as sponges, old socks and a thin paintbrush can be used for more effects.

7. Household items – you’ll find you need plenty of different sized circular objects for planet templates. Saucepan lids, old food cans, bowls and even the spray cans themselves can be used for this purpose. Just ensure that the items have definite edges, otherwise your planet edges will be fuzzy.

8. Cleaning fluids – some kind of white spirit such as turpentine will help to clean your tools after they get caked in paint and it can also be used to remove paint from your skin.

This completes the rather exhaustive list, but you can add anything that you think will work in a spray paint environment.

Another useful object is a paint fixative. Clear coat not only re-wets your current painting, so you can remove paint that had previously dried, but it also allows you to fix the painting once you’ve done, although you can show off like the youtube guys who use a lighter and a can as a flamethrower to dry the picture, but this obviously comes with inherent risks.

The aforementioned spray paint art supplies will get you started and well on your way to creating pieces of spray art. You can add to your collection as you progress, experimenting with different colours and cap types and you can always create new stencils and templates for more complicated designs.
Finally remember to keep simple things to hand such as cloths to remove paint and wipe things down and even a knee pad if you intend to take your artwork to the streets and paint for the masses.

From: http://www.spraypaintartpro.com/what-is-best-spray-paint-art-supplies