This is a general advice on "how to maintain right posture while riding any bike."
1)Most important is the handlebar grip position.Hand should be bent at elbows.The elbow should be at the same level as of handle bar, so that the forearms are parallel to the ground or sligtly below that level.This helps in taking shocks on hands rather on shoulders, because bent hand works as suspension.If anyone is suffering from upper back pain or muscle stifness near shoulder area can make use of this.
It also helps in better manueverability and control of the bike because one doesn’t put any weight or doesn’t use handle bar to hold on the bike.One is locked in to the bike for better ride in such hand position.
2)Feet should be placed on the footpeg such that brake can be accessible easily and at the same time, the feet should be bent at knees.The rider should always hold the tank tightly with the feet.This helps in bike stability and also one can steer bike with the feet.Steering with feet can help your upper body stay relaxed for longer time.
3)The torso should be kept upright or slightly leaning forward, but never digging upright.Because digging upright means pain below the shoulder area.This means keep your body upright but in a relaxed or slackened manner.Also if one sits leaning backwards on a cruiser, thinking it to be cruiser riding position, it causes pain in the tailbone or lower back area.
4)Also it is important to know that sitting way far behind can also cause problems as it did in my case.I started suffering from upper back pain because of the overstretched arms to hold the handlebars.Ideal is to see that by sitting where the hand is bent at elbows, elbow is parallel to handlebar and forearm parallel to ground.This is the **ideal place to sit and control the bike.
Please go through following article to see correct riding posture pictures.
https://womenridersnow.com/PublicFiles/DepartmentViewer.asp?ArticleID=1120