All you really need to start playing is an airsoft gun (gun, battery, and charger) and goggles. Yes, the other stuff helps, is very functional, or makes you look cool. But it's not really necessary...
Sometimes I'll just pick up my rifle and goggles and play using shoes, jeans, and a t-shirt... All depends.
Start by looking at how much money you would like to throw at this hobby, it can be a serious money pit (no joke) for enthusiasts. I strongly recommend going to a game as a spectator just to see how it all goes and what you personally like. As opposed to diving in head-first and then discovering you don't like it, after you've spent a bunch of money and waited for things to ship/arrive.
I suppose I'll start with these questions:
- How much money do you want to spend on everything (replica and goggles)?
- Does the replica you want have a battery and charging unit included?
- What is your playing style; Assault (Aggressive), Support/Sniper (Rear Guard Style), Quick-Mobile (Sneaky, Quiet, Flanking), etc)?
- What style of goggles do you want? Do you wear glasses or contacts (gotta know)?
- What type of terrain will you be playing on? Wet, dry, sandy, indoor, etc?
- Do you want camouflage? Do you care?