When you receive a new frog going into a newly set up enclosure, the frog will need to acclimate to its new surroundings. Covering three sides of the enclosure will reduce stress and also having the enclosure in a quiet place will also help.

I feed my Red Eyed Tree Frogs with a cricket bowl which is basically a small bowl placed into the substrate to hold the crickets. The bowl is slippery so the crickets are stuck in there. Usually any escaped crickets will eventually fall back into the bowl for later feeding.
This will also help in monitoring how well the frog is eating.

Make sure the crickets are no longer than the width of the frogs head.

I usually buy small crickets for my Red Eyes.

As for setup, if you use plenty of live plants and branches or vines, you will give the frog plenty of places to feel secure and climb and hide.
Your frogs are not usually found on the substrate and will move around the enclosure moving from branch to leaf to vine and so on.
Provide for that by having higher accents.

Also change your water at least every other day if not daily. You probably won't find they dirty the water dish that often but you still need to change it.