Like any sport, Skateboarding and Longboarding carry the risk of injury.

As for SKATEboarding, we will acknowledge that it is part of "street" skateboarding culture to not wear safety equipment. We fully understand this and therefore will not usually recommend safety equipment if asked, unless the skater is:
1)extremely young or
2)extremely reckless or
3)going to be skating bigger ramps and bowls.
In each case above, get a helmet and pads for sure.

However, we must emphasize that it is more important that the skater skates within his limits in a controlled environment and learns how to fall. A skater who does stupid things will get hurt, and no amount of safety equipment will prevent that.

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As for LONGboarding, we always recommend a helmet minimum regardless of what discipline you are into. Gloves are a must to learn how to slide, and pads are highly recommended too. At extreme speed, a leather suit for sure.
More importantly, don't do anything stupid, that means do not skate where theres plenty of traffic, do not skate a road that runs into more traffic, do not skate alone, do not skate blind corners without a lookout, be visible at night, etc.

Because longboarding typically involves greater speeds and the uncontrollable factor of drivers and their vehicles, it can be 100x more dangerous than skateboarding.

Unlike skateboarding, longboarders have a very pro-safety gear culture, and this is for a reason -- longboarders see a lot more serious injuries, and deaths are not all that rare and they usually involve a vehicle.

Longboarding is a sport that is very similar to bicycling, and with the use of public roads, you will always run the risk of getting hit by a car. The uncontrollable risk of traffic is something that bicyclists are usually well aware of, but still seems to come as a suprise to longboarders.

Be safe! Think before you skate!