Not knowing any details, I can only make some general suggestions. First look at how much all field positions have in common. Everyone should be working to score on attack, and everyone should be working to prevent a goal when not in possession of the ball. Everyone needs to understand each persons role in the system of play in both attack and defense. Everyone first needs to do what is expected of them, and then figure out what more that they can do to make the team successful. The field, ball, and technique does not change. Its a constant. So what does change is where you are located on the field. Usually you will be in the back and usually in the middle or defending third. Less time in the attacking third. Those situations will influence your tactical decision making. I guess my point is that regardless of whether you are a forward, midfielder or back, its a bad idea to dribble out of the back. As a forward you are not often faced with that situation, but as a defender you are. Ditto for defending with little or no cover behind you. You need to play conservatively as there is no one to defend if you miss a tackle. On the attack, you can support by running into a midfield supporting position or run into a winger position. But you are going to have to be conservative in when you make the moves forward (to function as a midfielder or forward temporarily) compared to if you were actually a midfielder or forward. Conservative not because backs should not attack, but because all the backs cannot attack at the same time. Someone has to stay home to maintain depth. I realize that this may not be really helpful, because you already know these things. But that is my point. If you think about it, you know what to do. If you have questions about your team's system of play, ask your coach. If you don't have a coach, ask your captain or one of the other experienced players that you respect. Typically the keeper or a central defender will organize the back line during games, so they are a good starting place for questions too. Good luck.
I began playing soccer as an attacking winger, until I met a really helpful player(who is one of my best friend and coach). He told me to play as a left/right back. These are actually the best positions to play soccer, because you have vision of the whole field. You will have to be conservative when you have the ball at the back, but you can still attack. Just gotta be smart about when to attack and stuff. And you will need lots of endurance if you're going to play as an attackin defender. Attacking from the back is actually easier than attacking as a forward or midfielder, because usually the other team's defense will be defending the attackers. So I snuck in goals here and there, not as much as the forwards, but I do score now and then. I don't play central defender tho, so I can't really help you with that one. But honestly if you're athletic and smart, you can play any position.
HONESTLY I THINK DEFENSE IS GREAT I MENA ITS LIKE YOUR THE LAST LINE OF DEFENSE I THINK MOST OF THE PLAYS MADE ARE FROM DEFENDERS (sorry all caps i just realized it was on)
Depending on which position your playing in defense, but most likely since your going from forward to defense i'd say your going to be right or left back. The best thing to practice is your passing and field vision. Something that separates good outside backs from great outside backs is vision to see a play develop in front of them. Hope that helps