It's perfectly fine to read the cards upright all the time. In fact, I do too. However, you have to know that you can also read the reversal meanings into an upright card. It works like this: imagine that each card is actually a pole or a stick. At each end you have the extreme meaning of the card; positive and negative. The correct degree of meaning for your reading is somewhere along that 'stick'. It's your talent, as a reader, to use your intuition to determine where on that scale the meaning lies.
To help you, have a look online at images for the Revelations Tarot by Zach Wong. He has built the reversals right into the image. So it's all contained within the card.