If you are difficult to see it is obviously difficult to shoot at you. Camoflage does not necessarily mean an "army look" - Use whatever works best for the particular locale you'll be playing in. In a wooded area, green and black or woodland style camo is best. In an urban setting (houses, junkyards, etc), go for +patterned clothing, with blues, blacks and reds in them.

Another very important feature is a visor on your goggles, the visor will not only increase the protection factor of your goggles but will also shade your eyes from the sun, which coming through your goggles can blur your vison and make it very hard to see. Not only that but sunlight reflecting off goggles looks like someone flashing a signal mirror saying, "Hey! Here's my head - shoot at it."

Ultimately, the art of "blending in" comes down to two major points:

1)Lack of movement, and

2)Lack of overly bright colors.

To get a little technical, the human optic system picks up both of these things before anything else. Movement is the number one thing, here - with minimal camoflage, it is possible to stand COMPLETELY IN THE OPEN and not be seen (I've done this before)...as long as you are absolutely still. The human sight also picks out shades that are brighter than the surrounding colors WAY before it detects colors that are darker.

This means that true camoflage isn't always the best answer, as too-light camo will stick out like a sore thumb even when compared to someone wearing navy-blue clothes in a woodland setting. What does this all mean? In a nutshell, move as little and as slowly as possible, and make sure your clothing is as dark or darker than the majority of the terrain you'll be playing in. (As a side note, Army surplus stores are the absolute best place to pick camoflage outfits up at.)