Let's talk about how to wear an accordion. First of all, when you pick up the accordion, you always want to pick it up by the two straps on the top. I usually say right arm first, just because it's the longer strap. Usually people have that one set up so that when you're playing, you have a little bit more leverage. So this one is usually a few ticks out longer than the other one. Also, be very careful when you pick up the instrument. People don't realize sometimes these straps tend to get caught over the keys. It's very bad for the instrument, so be very careful when you pick it up to not let that happen.
Most accordions have two connectors on the top and the bottom that hold them closed or open. Go ahead and unhook that, and very carefully try to attach it, and the top one as well.
Also, for your left hand, there's a leather strap that acts as a guide as you move up and down the instrument. As you're playing, when you're pushing and pulling with the bellows, there's a lever on top that allows you tighten that or loosen that, which makes it easier for you to play.
The straps are sort of up to you. People differ in where they like to have them sit. I do like to have mine different, but whatever works for you. You need to find a great place that feels comfortable for you, with the instrument. And also, if you think you're going to be standing for a while, or sitting, there's a back strap that you can purchase that sort of adds extra support underneath the instrument, so that you don't feel pain in your back when you play. A really good investment.
Once the accordion feels comfortable, you're all set to play.