I've played my fair share of basketball (SF/PF) and here's really all the advice I can give you.
The only way to make a good jump shot is practice. Get a form that you are comfortable with and just shoot. Practice doesn't make perfect, but it makes it a hella of a lot better. The only tip I can give on that is make sure the ball comes off of your fingertips. Try to get a good arc in there as well.
The only way to increase vertical is just working out your legs. There are some exercises you can do like touch the backboard (or the net) 10 times and then gradually increase that number. Also you can reach as high as you can on your tip-toes for 10 times until that number gradually increases. DONT SKIP LEG DAY!
For dribbling you can set up some cones and do weaving drills, or do the dribbling with 2 basketballs thing. Practice. As for passing, like mde said, it's all about confidence. If you have an open layup, take it! Open shot? Pop it! It's great to have that mentality (because I don't) because you can get an offense moving but it's pointless if you're giving up free points.
Hmm, I think that's really it... oh yeah.
RUN 4 YO LIFE! LIKE GET OUT WHILE YOU STILL CAN! BALL IS NOT LIFE!
But in all seriousness, you gotta run. That's where the speed and stamina come in. Sadly, suicides will be that one friend that you hate, because they never go away. Also time yourself to actually see improvement. Speed=/=Agility. Get those feet moving.Get everything moving. Up-downs or whatever their called will help if you want that extra push.
A friend who could practice/train with you would work too. Just make sure that person is willing to put in as much work as you to help you both succeed. And if not, make sure this friend pushes you to do better. You can do this alone, but a personal motivator never hurt anybody.
I don't know how serious you about bettering yourself but that's an essential gist to how to start. And at the end of the day, have fun with it. This is my small input right here.