How Much of an exercise should I do per session to get results quicker?

Im starting a routine of crunches, leg scissors, reverse crunches and side legs lifts. How many should i do in one session to gain results faster? Thank you!|||I would start out with 3 reps of 15.|||I would think you could do them to failure............that's not bad, you are not dealing with heavy weight, just repetitions. Try it and see how you like the burn in feel..............if it's to much just back out a little to what you feel good about. Good luck with your program.