Your friend is completely correct, but you aren't completely embracing what he told you. For the first 20 minutes of every game, you have to look at it like you are playing a one-on-one game (or two-on-two if you are in the bottom lane). You need to focus on your own play and how you match up with the guy on the other side of the lane from you. If you are asking for assistance from your jungler, you aren't owning your own play. You should be able to make it through the laning phase without giving your enemy team a huge advantage by getting murdered one-on-one. If you go down a kill to your lane opponent, start playing more passively, farming up minions and sticking close to your turret. Don't feed extra kills by picking fights with your lane opponent when they are up on gold and items on you. It's better to play passively, build yourself up, and be of benefit to your team later in the game than giving your opponent an even bigger gold/experience lead.
If your lane is being camped by the enemy jungler, place an extra ward and farm even safer. Ping out when you see the jungler and let the rest of your team know that you have that person's attention. That gives the rest of the lanes a chance to be more aggressive and go for their own kills when you have that focus on you. That also gives your jungler a chance to make a choice: help turn around your lane with a counter gank or pull of a gank of his own in another lane for a 2v1 and snowball your team.
If your support isn't communicating, you need to be comfortable in your own play that you can take on the bottom lane on your own. Your support isn't intentionally going into the game to feed the enemy and lose. They want kills. They want to win. If they are aggressive and making trades with the enemy, back them up. If they are playing passive, don't dive in on the other team. You know that you aren't going to get back-up on your aggression, there's no reason to try it.
You are right. Being positive and trying to be that glue that keeps the team together is a big step toward collecting a win. Keeping your head up and marching on when things don't start off ideally is one of the hardest things to do in ranked. It's even harder to do in normals. You will find all kinds of players going into normals to try out champions they have never played, work in lanes they are not familiar with, or pulling out the mysterious full AD Ahri or support Lucian. There isn't anything that you can do about that. But you can try to adapt your outlook of the game and try to push past those challenges by embracing them. Adapt and overcome, they say, but it's true. Who knows? That support Lucian could be a great advantage when you go to make a trade with the enemy and suddenly you find yourselves a couple kills ahead (even if your "support" gets those kills). A win is a win.
Ultimately, this game is a game of experience. The more you play, the more you experience, the more you see, the better you will improve. Remember the situations that you have been in and learn from them. Remember item builds that worked particularly well for you. Remember champions that you feel comfortable on and a strong affinity toward. Learn the kind of player you are and improve yourself. This will ultimately be how you can see your win rate going up. Practice in AI games will only get you the base mechanics and map movement. Now you need to learn the unpredictability of PvP to reach that next plateau of skill.
Good luck in your climb.
