Make sure to choose a meaningful person, place, or thing. Before you begin your paragraph, you have to be sure to pick something that is worth describing. If you want to describe a character, make sure the person is interesting in some way. If you want to describe an object, make sure it has some deeper meaning beyond itself so you have enough to write about. If you pick a place, make sure you can describe it in a unique way that can capture a reader's attention.
For example, in the opening pages of The Catcher in the Rye, Holden Caulfield describes a baseball mitt. The mitt itself is not that remarkable, but he describes it in a way that fills it with meaning because it used to belong to his deceased brother. Though not every object you describe needs an elaborate backstory, if it has some meaning behind it, this can help the description carry weight.
If you want to pick a place, don't just pick any old spot at a beach, but one that is meaningful to you -- or, if you're writing fiction, to one of your characters -- in some way. This can add a layer of depth to the place in question.
Introduce the person, place, or thing you are describing. If you want to get the reader's attention, then you should let him or her know what you're describing as soon as possible instead of leaving them guessing. Here is an example of some opening lines in a descriptive paragraph:
Natasha's basement was our sanctuary. I return to it in my best dreams and wake up feeling like I could die happy.
These opening sentences introduce the subject that is being described, the basement of the narrator's friend. They make it clear that...