I have a couple of 3-card spreads I use a lot because they are quick and easy and work for many types of questions. The cards for both are laid out in a simple line - 1-2-3 ... and each position has a "meaning";
Issue - Blockage - Advice
This is very useful for fairly specific questions like "why am I angry about such and such", or "how can I control myself regarding this other thing". The first card kind of cuts to the chase about what the person is REALLY asking about, the second is what may be holding them back or getting in the way, and the last is ... well, advice. Say a person wants to know why they can't find a good romantic partner, this would work quite well. Or maybe they're having a problem with breaking a bad habit (like unhealthy eating habits) - again, this spread would work well.
Another is; Past - Present - Future
Very good for a general reading where the person doesn't have a specific question. Usually, for me, with a 3-card "PPF", the card for the Past looks back a few weeks or so, the Present is what's going on right now (obviously this can be within a few days of the reading) and the Future card looks ahead a few weeks to a month. The nice thing with this is, if you want to look deeper into the past and future, you can expand it out to 5 or 7 cards, with each additional position on either end adding a few months to the time line;
Past - more recent Past - Present - near Future - Futre
Something like this might look 3 to 6 months into the past and 3 to 6 months into the future.
As I said, 3-card readings are very useful and flexible. The one I actually am using the most right now is a daily "Theme - Challenge - Lesson". This gives me an idea of the overall way the day is going to go, what will challenge me personally and a lesson I can learn from these.
Hope this helps.