Lots of shooting may not help. Practice only makes perfect if you aren't reinforcing bad habits.
Best thing you can do is to STRETCH. Get your body used to getting up and down and getting into position. I find that stretching my neck is the most important of all.
The hardest mechanical thing is the Loop Sling. If you don't have a sling that can do the Loop Sling on your rifle, think about getting one. As always we recommend the (cotton) M1 GI Sling as it is cheap, ubiquitous, and just plain works.
This blog post describes the Loop Sling technique in detail. Practice getting your sling on correctly.
Third item is to zero your rifle, and be very familiar with its sight adjustments. If you need tools to make adjustments, bring them with you.
As always, have fun. Bring a friend.
For your grandson, if he's not old enough for all the positions, we'll have him shoot from a rest and concentrate on Six Steps, NPOA, etc. Still plenty to learn. We often have younger folks on the line, it's no trouble at all.