According to this survey conducted by people who probably know what they're talking about, most people looking at dating profiles base their first impression of someone on their smile (76%), eyes (69%), and clothes (56%).
So basically you have to look good.
And as much as I love that the statistic there is 69%, you can't convince me that many people ACTUALLY look at eyes first. Otherwise, I wouldn't have had so many discussions about how my green and purple eyelids aren't natural.