Being able to take a shower with adequate water pressure and volume is important for rinsing off the soap and shampoo. Without it, you could be left with soapy residue that is not good for your skin or hair. Fortunately, there is a relatively simple and easy way to fix this problem without spending a ton of money.
Take your shower head off with a wrench and check to see if it has a flow regulator. Because of the concern for water conservation, almost all shower heads have this now.
Take out the rubber washer that is on the inside of the threaded end. You should then see a small plastic insert behind the area where the rubber washer was before you removed it. It will have a considerably smaller hole than the width of your shower head arm.
Remove the plastic insert. If it has a screen then clean any debris from it.
Scrape around the hole in the plastic regulator with a screw driver to widen it and allow for more water pressure and volume to get through.
Replace the plastic regulator, screen and rubber washer, and reattach your shower head. You have now increased your water pressure and volume in your shower.