I'm not sure how to provide more tips without outright spoiling the route, and there's already a route spoiler available in the game walkthrough PDF

Are you hanging out with Kyle at every opportunity? Talk to him in the mornings before you leave and ask him if he wants to join you (even if he declines), examine all the objects you can, on day two you should hit the beach before groceries (and examine the grill before heading to the beach), and go swimming on the first day he goes to the beach with you, and don't bother him when he's engrossed in TV (especially the first evening)