You get the choice between two different approaches to the Jewel Store, one being the Loud Approach and one being Smart. These will result in completely different missions and both have different setups.
This mission will begin once you have completed Carbine Rifles, which is the only required setup mission. The mission is being written as if you hired the best crew members.
Meet up with everyone at the garment factory and after the debriefing is over, get in the vehicle with everyone else. Drive to the jewelry store, listening to the conversation on the way there. When you get there, you'll head inside the store and should immediately go for the cases when the short scene is over.
Your crew should be fine holding the people up inside the store, so you can concentrate on emptying all of the cases with jewelry, of which there is a total of 20. They are all marked on your mini-map as green dots, so once you've cleared them all, head outside and control will switch over to Franklin.
You now have a four-star wanted level. Follow your other crew members on the bike until you jump off the overpass. Pay close attention when you do that, as you will need to make a right into an underground area. Keep following them until you come back above ground, where control will switch back to Michael, who is driving a big truck.
There will be cop cars chasing after the bikes and all you need to do is hit them once to incapacitate them. There will be a couple right away and then some that are hidden at first, only to appear when the bikes have passed them. Once you get the cue they're all gone, drive to the end with the truck and when the bikes are loaded, go to Lester's lock up to finish the mission.