Tattoo sleeves are named as such because they cover the tattooed person's arms like clothing sleeves. These massive tattoo projects are a large undertaking that can take hours upon hours to complete. The end result, however, will be with you forever, so it is important to put some thought into how you want to start your sleeve --- it's not as simple as just getting a tattoo and adding on additional ones until your arm is covered.
Decide what type of sleeve you want to have. Sleeves mostly vary in length (full sleeve, three-quarter sleeve, half sleeve and quarter sleeve) and colour (full colour, black and grey or a combination of both). Take into consideration whether your workplace allows exposed tattoos before beginning the sleeve process.
Decide what you want your tattoo sleeve to be composed of. Some people have sleeves that are composed of tattoos that fit a particular theme while others simply get tattoos that they like. Also, decide how many tattoos you would like your sleeve to be composed of. Some tattoo sleeves are made up of a single, cohesive tattoo piece, while others are made of numerous smaller tattoos.
Decide what piece of work you would like to be completed first. It is best to start with a tattoo that will be able to stand on its own if you never get around to finishing the sleeve (or decide you do not want to). The same goes for the placement of the tattoo; place the tattoo somewhere where it can exist independent of the rest of the sleeve. As a general rule, start on the upper arm area first and work your way down the arm. That way, you can shorten the sleeve length should you wish.
Look at the tattoo artist's work prior to letting them start the sleeve. This ink will be on you forever, so you want to make sure that it is going to look good! If the tattoo artist wants to draw the piece freehand, ask if you can watch them do so on a piece of paper first. Otherwise, have them draw a stencil of the tattoo beforehand so you can make sure the tattoo meets your specifications.