You can have 1 full armor. In addition, you can have a number of armor accessories. The only restriction on armor accessories is that no two accessories worn at any time can take up the same slot. See below for the current slots. For example, you cannot wear a Flack Jacket and a B.D.U Jacket together, because they are both in the Chest - Over Clothing slot.

Feet
Hands
Shoulders
Chest - Over Clothing
Chest - Under Clothing
Legs
Shins
Forearms
Full Body - Over Clothing
Full Body - Under Clothing

Shields

Shields are a unique type of armor. They can be used with any other type of armor, but they can also be used as a melee weapon, if the need calls for it.

There are three types of shields: Bucklers, Round Shields, and Tower Shields. These include anything from medieval-style shields to modern-day riot shields.

Bucklers can be used with one-handed or two-handed weapons with no penalties. They cannot be used with two separate weapons.

Round shields can be used with a one handed weapon with no penalty. They can be used with two-handed weapons with a -3 to hit penalty.

Tower shields can be used only with a one-handed weapon and not two-handed weapons.

You can dual-wield a shield (as a melee weapon, +20 dam) and another melee weapon, but you cannot dual-wield two shields without the proper skills.

For details of how to calculate HP, see the "Stats" page under "Game System".