There are many different types of picture hooks.
The type of picture hook you want depends on several different factors.
Firstly and most importantly, you need to know what type of wall you have.
There are four main types of walls that people deal with on a regular basis.
Drywall (also known by its most common brand name Sheet Rock), Plaster, Concrete (or cement), and Brick.
There are two different categories of hooks.
There are ones for use in Drywall and Plaster or ones for use in Concrete and Brick.
Picture hooks are also designed to hold certain weights which are designated on their packaging.
The most common picture hooks used in Drywall and Plaster are steel with regular common nails, brass hooks with smaller black hardened steel nails, hook and loop (Velcro) self adhesive picture hooks, push through hooks, and anchored hooks among others.

• The common steel hooks with common nails must be mounted to wood studs or wood lathing behind the wall.
  So it limits the potential places that you can place your frame.
  Wood studs are only every 16" on the center of them.
  Although this is the most inexpensive choice a stud finder is needed to find where the studs are behind the wall.
  
• The brass hooks with smaller black hardened steel nails often referred to as ook hooks are able to be mounted anywhere on the surface of the wall that you want to put them.
  The reason being for this is that the hook has more surface area gripping the wall thus using more of the wall for strength.
  Also, in the heavier pound rated hooks the weight is spread across more than one nail sometimes of a thicker gauge.
  
• The hook and loop (Velcro) self-adhesive picture hangers are definitely the easiest ones to use but they can only hold a maximum of 10 pounds.
  Bathrooms and high traffic areas are also probably not the most ideal place for these hooks because of the moisture in the bathroom and possibility of being knocked into in the higher traffic areas.
  
• Push through hooks are also pretty easy to use and can hold as much weight as the nail in picture hooks.
  These look almost like a section of a lightning bolt.
  The reason that it works is that one side of the hook is resting on the wall while the other is being pressed into the back of the wall on this inside with equal pressure.
  The only downside that I see with these hooks is that they often stick out from the wall farther than regular hooks.
  
• There are two types of picture hanging systems that you can use anchors with.
  There are the ones which are just a hook where you can stick a screw into and then there are also those that have wide mounting plate which has a level built in so that you can get a perfect level for your frame.
  The simple one is often only for lighter weight pictures.
  The ones that allow multiple points of anchoring are very secure and the flushest way to mount your picture to the wall.
  It is also the most secure method as well.
  It is versatile enough to use on any wall surface.
  The only downside is the amount of work it takes to mount it.
  

The most common hooks for concrete and brick usage are nail in hooks with a cushion on the nail for when you hammer it in, brass plated nails with hooks, and small pin hooks.
These hooks all have hardened nails used specifically for cement surfaces.

• The steel nail in hooks with the cushion are very handy in that there is less impact on the wrist when driving the nail in.
  
• The brass plated hooks are more decorative and also spread the weight across a couple of nails in the higher weight versions.
  
• The smaller pin hooks also spread the weight over multiple nails but this is only for lightweight frames

When installing the frames into the concrete walls it is fine to put the hook anywhere that you would like.
When installing the hooks into a brick wall make sure to install the hooks into the mortar between the bricks otherwise you may split the brick.