Be selective–and restrained–in using exclamation points and italics. More than one of these every few pages probably means you are using these visual markers to shore up weak word choices. Journal editors, agents, and publishers will immediately tag you as an amateur.
You might, rarely, create a character for whom exclamation points or the verbal stresses represented by italics is part of her (or his) voice. Even in this case, take care not to overdo it. And be particularly stingy in using these markers elsewhere in the manuscript.