This is my personal guide on airsoft. I attempt to cover every important aspect I could think of in the next slides. I go over weapons, clothing, strategy, and much more!
Each weapon has advantages and disadvantages. My personal favorite is the shotgun because of its power and high rate of fire (if your shotgun is pump action at least). Your chosen weapon usually comes down to your playing style. If you don't move around much a sniper rifle might be a good choice. However if you never stop moving and attacking others then a machine gun would be a much better weapon for you.
Note: If you play with C0H2 or Gas guns these descriptions may not match your weapon.
Advantages: Powerful, Great Rate of Fire, Large Magazine
Description: The shotgun is a good weapon for close-medium range combat. It has decent accuracy & range. It also has great power. If you can find a pump action version you will be able to have a very good rate of fire. In addition, Shotguns generally have large "drum" magazines capable of holding hundreds of BB's which eliminates to reload or change clips often.
Advantages: Accurate, Good Range, Decent power
Description: The rifle is best used in medium-far combat. Its accuracy allows you to attack from a safe distance. It also shoots faster than a sniper so you can take more shots closer up. A good rifle should have good long range accuracy and a decent rate of fire.
Advantages: Very Accurate, Great Range, Very Powerful
Description: The sniper is a long range weapon. Some snipers come with scopes, although personally I find hard sights are more efficient at multiple ranges. The main perk of the sniper is it it allows you to pick off enemies from a distance without being seen. Also, most people will be scared of the snipers power which will force them to get under cover more often. Pared up with a spotter, the sniper is a capable weapon.
Type: Machine Gun
Advantages: High rate of fire, All around good weapon
Description: Great for "assaulting" the enemy, the machine shoots faster than all the other gun. Power and accuracy usually aren't very good though. Very good all around gun that works great in almost all situations