Everything said above is right on concerning dumbells. The only other bit to add is of course..start your sets with your weaker arm, i.e. your left arm.
Also, a buddy of mine used to do this. If he came to the gym to do back and biceps, and normally a person would do their back work first then their bicep work. He would start his workout with his weaker left arm. In other words He would do bicep work first for his left side only. Then do his back work, then finish with his right bicep work. His theory was your are fresh and strongest when you first walk in, so his left arm would be ready to handle heavy right away.
NOTE: Many may feel but dfoing that left bicep first may screw up his intensity on his back work for his left lat, but he used power wraps so it didnt really matter.
Sorry for the novel above.
Peace