I have been decorating and painting old liquor bottles, canning jars and anything else I can get my hands on. And it is all actually pretty easy.
My bottle above was decoupaged with napkins. I picked out some pretty napkins then peeled the layers apart, as you only want one layer. I cut the flowers out and then used decoupage medium to apply. I applied the decoupage medium to the bottle then laid the napkin down carefully. Be very careful, these do rip easily. I was going for a vintage look so did not worry about wrinkles. There is a method to make your decoupage wrinkle free that I will post about at another time.
The painted jars and glass first must be very clean, I wash them with Dawn detergent and rinse well and are painted with chalk paint and either finished with an acrylic sealer or wax to seal. I also usually sand to distress them.
Give it a try you will love the results!