Storytellers generally agree: If you ain't got it, don't use it - accents, that is.

Accents are difficult. Unless you come from a specific culture, you shouldn't use them. In Liz Warren's The Oral Tradition Today: An Introduction to the Art of Storytelling, she cautions, 

"It's risky and can easily end in failure and offense. Here is the bottom line: only use an accent or a dialect if it is one that you have mastered and you know you can use with integrity and without causing offense."

Even most actors have a hard time with accents. If you look at the credits at the end of any movie where an actor uses an accent, you will always see a dialect coach listed.

Liz Weir has said that, "You really can't affect an Irish accent, as they change geographically every fifteen miles!"

Two years ago I was in Dublin, buying a ticket on the ferry to England. I stopped a man at the station to get some information and clarification about where to board. He knew immediately that I was from America (duh) and we chatted for a bit. Before parting, I said something to him, trying to use what I thought was an Irish accent. He turned to me, screwed up his face, looked me right in the eye and said, "That's the WORST Irish accent I have ever heard!"

'Nuff said.