A lot depends on whether you are using a standard BCD, or a backplate and harness. You have gotten a lot of answers on how to route the 7' hose with a harness. If you are using a standard BCD with big integrated weight pockets and no straps at the waist to speak of, what you will have to do is route the hose under your arm, up across your chest to the left side of your neck, behind your check and around into your mouth from the right. This will leave you with a great deal of slack hose in front of you. Double this up into a loop and stuff it through your waist belt or cummerbund wherever you can. Keep the waist belt tight, or the hose will constantly be escaping.