Doing sets of no more than 45 bicycle situps at a time will help make ur abs fitter at an alarming rate, making you better at regular situps. If you can't do 45 bicycle situps, do sets of 25. Once several sets of 45 get easy, start wearing shoes when you do ur bicycle situps.
For pushups, just do 10 pushups whenever you are in the mood and try to get as many cumalitive pushups a day as you can (shoot for 50 for now). If that is not intense enough for you, schedule in a ladder workout for pushups once or twice a week (anything more will leave u sore, delaying ur training in the next few days). Start with: 5 pushups, 10 pushups, 15 pushups, 10 pushups, 5 pushups.