First Impressions

When laying down a spread, it is useful to take a few moments to look at the spread as a whole, before reading individual cards. Is there a preponderance of one suit? Are there several Major Arcana, or several Court Cards?
These are indications that you should keep in mind when doing the reading. They are often clues as to what is going on. For example, lets say the question concerns ones love life. You throw the spread and see there are lots of pentacles, but not a cup in sight.
What does this mean? It could mean that material security is a key issue in the relationship right then. It could also mean that the person should be focusing on financial matters right now, rather than the relationship.
Perhaps worrying about the relationship has led to them doing poorly at work, or to spending more than they can afford to keep the other person happy. Perhaps they are telling you that the issue is love, but the thing that is really worrying them is money.
Tarot sometimes tells us what we need to know vice what we want to know. You might want to ask questions to explore these issues during the reading.

Last Impressions

When I have finished interpreting each card in a spread, I like to sum up the reading. I just review the overall reading, pointing out the key points we covered. I always try to leave a reading on a high point. Even if the reading conveys bad news, I try to give the querent the tools to change events, based on the reading.
A reading should be empowering for the querent, rather than a recital of things that may happen in the future. The key words are "may happen". We have the power to influence and change the future.