Even if you're not a particularly handy sort of person you shouldn’t have too many problems installing your own medicine cabinet and by doing it yourself you’ll save a pile of money.
Fitting a medicine cabinet is fairly easy, requiring a bit of common sense, a few tools, eg - spirit level (to ensure the unit is mounted squarely), a slotted or cross headed screwdriver, a tape measure, a pencil to mark the position you want the cabinet, and a power drill with suitable drill bit.
Plan Your Installation
Planning is always the first step. Measure out the area that you have to work with in your bathroom. Decide whether it’s to be a recessed, built in medicine cabinet, or a more conventional surface mount cabinet. Make sure that the mounting surface can take the weight and that it's suitable for the appropriate fasteners.
Height of the Medicine Cabinet
Height is a vital consideration - you want to be able to access it easily and if it is a mirrored medicine cabinet take into account that the whole family would like to use it, so bear in mind their heights too. But then it shouldn’t be set too low - you don't want small children harming themselves by getting at the wrong medication.
The general rule of thumb for a medicine cabinet is that the top of it should be 72 inches off the floor. You will also need a stud locator to make sure there is a stud in the right place for you to use. If it’s a drywall you will need a hacksaw blade to cut through any drywall screws that attach the stud to the drywall so that you don't pull the drywall apart.
Surface Mount Medicine Cabinet
Installing a surface mounted cabinet is much simpler than the built in kind. You will need to use either a stud locator, as with the built in kind, or plaster or drywall mounting equipment.
Mark out your line by using a carpenter's level so that you do not get the cabinet crooked, then holding the cabinet in place and ensuring that it is in a correct and level position, mark where the fixing points need to be on the wall. If possible try to get someone else to hold it, even the smallest of these cabinets can be fairly heavy or if this is not possible, support the cabinet somehow whilst fixing it in place.
Depending on the weight and size of the cabinet there will be either two, three or four fixing points. After carefully doing that, drill your holes into the drywall, plaster or stud as you have marked. You may have to pre-drill holes. Remember that it puts more weight on a fastener if it is oriented toward the bottom so you should have some fasteners near the top.
Built in Recessed Medicine Cabinet
If you go with a built in recess medicine cabinet you will need to cut inspection holes to see what is in the way that could possibly cause problems. A plumber and or electrician may be needed to reroute pipes and electric lines. Then mark out and cut the hole that you will be fitting it into. You may also have to cut through a stud to accommodate the cabinet. Be careful not to damage the drywall behind the stud.
Install 2x4 boards cut to desired length in order to have something to drill into, and to block it at top and bottom. Drill your holes through side of the cabinet, secure in the screws and the equipment, and attach the door. You may wish to seal around the edge of the cabinet with caulking. Then stock your cabinet with your needs.
Final Note on Installing a Medicine Cabinet
NB - Once the cabinet is in place, before anything is put inside,check the mountings for safety and security.