Each step will be a different class of guns, with a listing and a description/suggestion.
Also, there will be only a general description. If you want more information about a certain gun, such as where to by it, please either reply or send a private message to oniman7 or jakee117.
Step 1: What are your uses?
what style of gaming do you like best? CQB(close quarters battle)?, Field?
Certain guns are suited to certain environments.
for example, an m16 would not be the best for cqb, considering it could prove very unwieldly around corners, whereas the mp5k, measuring about a foot long, is considered by some to be the ultimate cqb machine.
do you enjoy laying down a fearful rain of plastic on you enemies, or instilling fear and uncertainty with, few, well placed shots?
some things to consider are
*styles you like
*playing area (NEVER play on public land, this gives all airsofters a bad name, only used licensed fields)
*how much ammo you use
weight you want to carry
so, for field games, you would more than likely want a gun with a medium to long barrel length, good shoulder support, ect.
for CQB games you would want a small gun, one that could maneuver corners easily, and generally, with an fps of less than 350, (or be ready to pay to have a spring cut) so you can play at a local field (check your local field's rules of play and follow them, no one likes a dishonest airsofter)
If you play a good mixture of both, but don't have the budget for multiple guns, a carbine is a great option. These are considered the "midway" between long and short guns, essentially, they are the best of both worlds, I believe the most popular carbine is probably the m4, with the ability (with modifications) to play a cqb gun, a D esignated Marksman Rifle (DMR) support gunner, Grenadier (see the accessories page for more on grenade launchers) and countless other possibilities.
as far as budget, an airsoft gun can run anywhere from 10-5000+ dollars
for ammo, the only ammunition I would recommend using in any high end AEG (automatic electric gun) is highly polished, .20 gram bbs or heavier, which can run up to .40 grams and heavier.
Thanks to Jakee117 for this entire section.