Congratulations. Saving for retirement is very important. How much is an interesting question, it depends on many factors. Age is one. If everyone started saving 10% of their pay for retirement at an early age, we would have no retirement crisis in America. So this is a good goal if you are young. But you may have other obligations - debts that need to be paid, etc. It doesn't make a lot of sense to save aggressively if you have lots of high interest debt piled up! Plus, you should have a healthy emergency reserve fund (cash in savings for emergencies) before you start plowing lot of money into a retirement fund. About 3 months pay in a savings account is a reasonable minimum. Reason is that too many people in desperation end up tapping their retirement fund when things get tight - and this is a really bad idea. So as important as retirement savings is - don't stretch too far until you have your other financial ducks in a row.
I would say if your employer offers any kind of matching - you should put in at least as much as they will match. This would be true even if you do not yet have your emergency reserve fully funded yet.
I would also say if you are older (40s or 50s) and have not yet saved for retirement, then you should really start saving more aggressively. 10% may not be nearly enough and you need to set a higher goal. But once again, create your emergency reserve savings outside the retirement fund before you start to pile on the 401k savings.
Also as a server, not sure if your tips are included in your paycheck. You should be saving a % of your total pay, including tips, for the future.
Hope these guidelines are helpful.