Use the right tools on your tool.
We recommend using an electric trimmer with a guard that will ensure uniform length and evenness. Using scissors isn't a terrible idea, but since you're not a barber, you run the risk of having your dick rock the same asymmetrical haircut as Danny Brown. Also, scissors are much riskier in terms of slicing yourself. And you don't want to slice your dick, do you? (More on what to do if you slice your dick later)