How to use Off the camera flash

Guys,

I have been mainly using Wireless trigger to use the strobes, but was just thinking of doing some experimental work in outdoors and can't use the strobes in the outdoor due to portablity and power issue. I was thinking of using small flash guns or 580 EX II to light up. I need to know what are the options that I can use to sync these flashes because Infrared trigger is not working more than 5 feets.

radio triggers are probably the best bet - plenty of options to suit all budgets

I'm reasonably happy with the Cactus V4 triggers from http://www.mpex.com

Radio triggers will still be your best bet. You could look at an IR trigger like an ST-E2 but they don't work reliably outdoors. What kind of radio triggers are you using for your studio strobes? They may work on your speedlights as well.

Since it seems that you don't yet have "small flashguns", I would definitely recommend some manual-only flashes. And since you're already familiar with manual flash from studio strobes, it should be a piece of cake (and not such a big bite out of the wallet ).

For the flash, go for Yongnuo YN-460 or LumoPro LP120.
For the triggers, go for Yongnuo RF-602.