Formal:
* Jetez un coup d'œil à ceci. (Literally: "Throw a glance at this.")
* Veuillez regarder ceci. (Literally: "Please look at this.")
* Consultez ceci. (Literally: "Consult this.")
Informal:
* Regarde ça. (Literally: "Look at that.")
* Regarde un peu. (Literally: "Look a little.")
* Tiens, regarde. (Literally: "Here, look.")
For specific things:
* Lisez ceci. (Read this)
* Écoutez ça. (Listen to this)
The best way to choose the right phrase depends on the situation and your relationship with the person you're talking to.