I spoke to someone recently who said she was scared of patterns and feels safer sticking to block colours. Is that how it is for you or do you like to wear patterns? Are you sure what sort of pattern really suits you? Florals are still very much around for the Summer so if you would like to wear patterns - squares, florals, polka dots, paisley etc., but are unsure about them, I hope you will find the following ideas helpful.
First of all, choose one that has predominantly the most flattering colours for you. Then, as long as your not-such-good colours are less dominant, it will look good.
Secondly, you need to find a pattern that is the right size for you. If you have small features, you will look good in a small-scale pattern, whereas if you have larger features such a pattern will look at odds with you. You will need to choose a larger-scale pattern.
Thirdly, the contrast in the pattern needs to echo the contrast between your eyes and your skin and your hair and skin. For example dark-eyed beauties with white skin (a typical "Winter" can look good in black and white). If your hair and eyes are light you will be better in patterns with very little contrast.
And lastly, try and echo something about you in the pattern - e.g. my curly hair seems to fit with the circles in the pattern of my shirt.
Have fun and experiment!