We all know how to play league of legends, we wouldn't be on here if we didn't, so I wont waste your time with simplistic mechanics. As a support, the beginning of your match up until you destroy your lanes tower is focused on your ADC. If your ADC doesn't like what you're doing, stop it. If they tell you to do something, do it. If you think that you can be all smart and swap lanes you just might want to ask your ADC first. A nice thing to do is ask your ADC about how they will be playing before the game starts, things like if they want you to attack minions, if they want you to ward bushes or not, etc. It's always nice to do, and tips the game oh-so slightly in your favor. You also should communicate with your ADC. I know how simple it sounds, but it really is helpful if you understand that you and your ADC are central to each other. If either of you play in a lack-luster fashion, both of you will suffer. And as a duo, you're going to need to communicate. Find time to do it, as it's helpful. While your at base healing, while your walking to the tower, and any other situation where you can fit it in. Good communication is very important. Sometimes your ADC is just an idiot, and you may find yourself asking what you can do. You don't always have to stick with them, in my opinion. If they're stuck on pushing bottom lane while the inhibitors are about to get destroyed, it's possible that they might not be doing the right thing, and you should go help the rest of the team defend.