In tennis they call this putting the spin on your ball. I guess you're asking how much spin can you apply to your extracurriculars and experiences before your ball goes out of bounds.
My answer is your embellishments or spin have to be grounded in truth and authenticity. If you were called in for a college interview and questioned in depth about what you wrote on your application would you pass the truth test? Or would you start to stutter and find yourself unable to support that more grandiose representation because once there were queries about the details, you couldn't back up your statements. Here are two hacknayed sayings to live by. First, the devil is in the details. And second, better safe that sorry.
That said, I think what you can do is FRAME your stories and experiences in ways you may not have thought of. Do not underestimate the importance of holding a minimum wage job and scooping ice cream at the local sweet shop, or hauling golf bags for pampered members of a country club. These kinds of experiences do add value and substance to your college candidacy. Admissions officers have great respect for these types of jobs. They show you understand the role of being an employee, that you can handle yourself with customers, and showcase other characteristics like commitment, maturity and responsibility. Sound unimportant? Hardly - these are skills that easily transfer to success in college and life. As Seth Czarnecki (another contributor here) suggested, there are ways to represent your work experiences beyond just being descriptive. If you are a food server of some kind, perhaps you can play up what you have learned about serving different types of populations of customers, from little kids, to teens, to even elderly customers. This can showcase a sensitivity to others and awareness of a range of customer expectations. Of course, holding a part time job, and doing well in school is in and of itself admirable. It's possible you did not think of yourself and your college application in this way. But in a world where most students have dabbled in community service (because it's often required by the school), or started a charity of some sort (with Mom and Dad's help), holding down a good old fashioned job is admirable.
One important way to add safe spin, or frame your college responses, is to create an accomplishment statement in describing what you did. For example, if since you began working at the ice cream parlor, sales have gone up, even just by flavor or type, you might say, "Working at blankety blank I have helped sales of ice cream cones increase by approximately blank." Or perhaps you have suggested a better way to manage inventory to your bosses or business owners. This too can be massaged into an accomplishment statement. For community service you might also be able to make an accomplishment statement like, "Since tutoring Joey and Alex, these two students now have solid C's in algebra whereas before they had D's and were at risk of failing." The idea is to suggest you have somehow had an impact, however small. As for sports, maybe all you did is just make the team - there is something humble and refreshing in saying that, rather than trying to stretch the truth.
Most importantly, how far you go in expanding your job title, position, or role you played in any job or extracurricular should be subject to good judgement. Not just yours, but your guidance counselors or another adult. Enlist a second pair off eyes on how you have portrayed yourself on the college application. Giving yourself a nice sounding job title when your employer simply left it blank, or puffing up your role is perfectly fine as long as your ball stays within bounds.