You want a bottle brush. And any bottles you drink or pour out of you want to rinse and flush right away so they don't crust up inside. I rinse mine well then use hot water baking soda. and a bottle brush then rinse well with hot water again. If I have labels on them then I soak them in hot water,then run a small stream of hot water while using a small pan scraper to get the label off, oxyclean works though. I just use hot water and elbow grease. If the labels are really bad and sticky I use some goo gone for a few minutes then wash it off with a soapy rag and rinse again.
Use a bottle brush and rinse them really good inside. They also sell bottle jet washers to make it easier,just hooking it up to your faucet it uses pressure. Even sanitize them if you want then turn upside down to dry before storing. Then on bottleing day sanitize again, I like to flush them with hot water a little before sanitizing again though, that's just me. Try not to use crusty/moldy bottles, ever. Bad idea. Hard to clean and you need to be shure they are completely clean. Probably something pbw and a bottle brush could take care of though.