Irrigating is OK in some circumstances. Usually you can use a 10cc or 20cc syringe, usually with normal saline, or occasionally water. In the field, you can fake it with a ziplock bag with a pinhole in one corner.
Beware, though, that irrigation tends to splash. How much of someone's blood do you want on you?
You'll probably be fine just "rinsing" a wound with clean water (either boiled, filtered, etc). Do it enough to get out the obvious dirt and stuff. It's not as high pressure as a syringe, so you'll probably need more fluid. I'd suggest cold water (easy or hard, depending on your campsite!) if possible, cuz it may hurt, and the cold will help dull the pain eventually.....