In case you haven't noticed, I do not use reversals, however many people do. You can take a book and learn it's interpretations of reversals or you can take an easier approach and chose one of the methods of reading them listed below:

1. A block in the upright energy of the card
2. A delay
3. A subconscious wish or desire
4. A hidden or surreptitious energy
5. A weakened version of the upright meaning

There are many other methods for reading them as well.
The use of reversals is not as prevalent as it once was. Many newer beginner books do not include them at all, however you must do what you feel most comfortable with.
Arguments can be made for both sides. If you decide not to use them, bear in mind that each card has a full spectrum of meanings. For example, the three of cups can mean merriment and celebration, but carried to excess could mean drunkenness, or excessive partying.