Whats an easy way to get your 5 yr old son to listen to you with out having to raise your voice all the time?

My 5 yr old son somedays will not listen to me at all. I dontk now what im doing worong, but it seems to be getting out of control. I dont know if its just me or waht. I try my best not to raise my voice, but osmetimes i have to just so he will listen.
When i was a child my dad sometimes hit me and yelled at me, so im trying to avoid that behavior on my part as much as I can. because i dont want my son to have to deal with that stuff.
What can i do????