Vanilla Viper tactics:
ID as many enemies as possible before engaging.
Always fire from prone or behind cover.
Engage enemies indirectly whenever possible.
Stay near teammates: they have supporting fire and useful gear.
Running is only for escaping explosions and getting to cover.
When all else fails, hide!

A special message from the Commander:
http://www.youtube.com/watch?v=eqbF5IH4FG0&feature=related

Brings a tear to my eye:
http://cdn.screenrant.com/wp-content/uploads/GI-Joe-2-108.jpg