I can see advantages to going to a launch to learn from others there; viewing in person is better than looking at photos, talking in person is, in most ways, better than writing posts back and forth. Still, asking here is a whole lot more convenient for many, many people, including
@86mustang408w, apparently; there's not a reason in the world not to do both, even if attending launches is easy.
OK, addressing 86mustang408w's opening question, here are my methods: first step is to read this thread and others, and talk to folks at launches, to see what other people have done. Second step, er, um, TBD. I did my L1, long ago, with nothing but an upgraded Estes trifold, but that was on a surprisingly small rocket for an HPR. What I'll do on my next H/I rocket (my current stalled build) is follow the manufacturers instructions. What I'll do on my L2 (I'm aiming for early next flying season) I do not yet know, so I thank you for starting this thread.
The current kit has a piston, with shock cord attachment on each end. The attachment to the piston uses two parallel slots in each bulkhead. The shock cords are ribbons that go into the the baffle through one slot then back out the other, and then the whole arrangement is secured with epoxy applied generously over, under, and all around the ribbon; it's internal, so I wasn't shy about it coming out sloppy. The other end of the lower cord goes through a slot in the forward centering ring, flat up against the motor tube, then three or four inches of ribbon lying against the tube, and again the whole thing epoxied together, quite generously once again. The other end of the upper shock cord I don't remember (did I say this build has been stalled for a while?). Parachute attachment I also don't remember. I'll look and get back to you.
For the L2, here's what I'm thinking so far, subject to change: I'll use lessons learned from the current build, but adapted. There won't be a baffle, so there's only one piece of shock cord. That will be attached to the front baffle plate by the double slot method from the current build. The other end will be attached to the nose cone bulkhead. This will not be dual deploy, will use motor ejection, and a JL Chute Release; it's a cert flight, so KISS. I'll get fancy on a later build.
And emphasize, this is all subject to change as I learn more from here and from club members.