If you are coming from west, 210 -> Sierra Ave exit, turn left -> go under I15 -> Glen Helen Pkwy, turn right -> straight, go under I15 again then merge back onto I15. It will save you a lot of time. The construction on I15 between 210 and and 215 is still causing extensive delays during peak times.
On a side note, if you don't make the right turn onto Glen Helen and keep going you'll enjoy a nice winding road with great mountain views, smells and crisp air ... and if you do it right, can also navigate back to I15 with careful routing.