Resistance Curl
Adding resistance in the form of a resistance band will effectively increase the level of difficulty for a number of exercises it can be used for.
With all exercises, aim to keep the tension on the band, as this will enable the muscles to be under contraction throughout the movement.
Its essential that you fix the resistance band to a secure object, and position yourself so that the tension is not to hard for you to finish the final phase of your chosen exercise.
Focus on a smooth action throughout the complete movement, avoiding any jerking movements, always allowing the tension to be released from the band under complete control.
All levels should work for a comfortable amount of reps maintaining good form throughout, its important to realize that by adding resistance you will reduce the amount of reps that you can normally perform.