Help! How Do I Keep My Plants Alive?

Ok I'm really trying to keep up with my yard this summer, trying to make it pretty and not disappoint my neighbors. 'Keep Rebecca's Block Beautiful' is what I'm going for, so I got some pretty new plants for Mother's Day, a gift. I love them! Beautiful, colorful flowers that were thriving...

up until about a week ago. I don't know what happened. I'm sad. They were alive and well 1 minute, now they're sad and dying. I know what you're thinking, JUST WATER THEM. I do. My momma even taught me how to buy the ones that require little or no sunlight, depending on which way your house is facing or not facing the sun, etc. I water them once a day because I know the sun soaks up the water but beyond that, what do I do? For those of you that DO have a green thumb, because clearly I don't, any advice for a 'plant killer?'