Pull ups, push ups, rope climb (without using your legs), Kip-ups, deep shoulder-shrugs while in a handstand, etc etc. Lots to choose form.
Putting yourself on a daily program that has REASONABLE goals and designed for success is the key. There is a saying: "Don't train to failure". Meaning, avoid doing "as much as you can until you can't". That type of program only works when you have a trainer or coach to motivate you. When self-training though, it doesn't build motivation when you fail. And consistant motivation is even harder to maintain then the training itself. So - Train to succeed.
First, Test yourself. How many Push ups, Pull ups, and Kip ups can you honestly do (without cheating!). Your goal is to do two more then your last test cycle on your next test cycle. It doesn't matter how many you do. If you can only do 4 push-ups, then that's all you can do. It's OK. That's why you set goals for yourself.
Keep a progress chart and update it (re-test yourself) every two weeks. No sooner.
Then everyday, do 75-80% of your tested ability - then stop. If you can only do 5 pull ups, do 4, but make a point to do it everyday, not just a couple times a week. After two weeks -- test your new ability. This higher number (and it will be higher...trust me) now becomes your new baseline. Then just continue from then on.
Oh yes, and no being lazy either. When doing your exersizes, there should be no more then 3 seconds between reps. Not 10 or 15 seconds. I call that cheating.
Last November, my DD Nastia (9) couldn't more then 3 pull ups (without cheating). Now, she can do 15. She also struggled with leg-ups on the stall bars. One or two was the max before collapsing. Now, 12 is her limit, so everyday she does 9 or 10. Push ups are still behind at 9, but, she's working on it. Her progress is her motivation, which is why it's important to chart it. When she re-tests herself, and gets to her limit + 2 (or 3), she's so happy with her new ability that she can't wait to show everyone she knows.
Lastly - avoid junk food. Few things zap your natural capabilities then eating or drinking junk. A Sugar rush isn't real.
Anyway - that's my suggestion. There are many ways to train... but you do have to train.
Tim