These can be as simple or as complex as you wish. Some are very intricate, some are simple. There is no right and wrong, just use the spread you feel most comfortable working with.

I personally work with very simple spreads. The complex ones are great, but not for me. I find the results are the same no matter which spread I use.

Sometimes an additional "mini-spread" is required when addressing a particular issue which needs more in-depth exploration during the reading. Don't feel there is a right or wrong in adding a mini spread, add one if you feel it is necessary to bring clarification. 

A single card from an additional tarot or oracle deck can sometimes bring the last piece of the puzzle together, this is why I always select two decks to be on the table as I work.

Try searching for more about the following spread layouts on the internet:

The Celtic Cross, The Diamond, The Flying Bird, The Key, The Mirror, The Pyramid.

Here is The Celtic Cross spread :