The bigger the litter tray the more hay you can put in to encourage your rabbit to eat hay whilst he poops.
Bunnies don’t like other animal smells (They will think there is a predator close by and will probably thump their back legs. So wash your hands and maybe even change your clothes if you have been around other peoples pets).
Learn to gain their trust slowly. Let them come to you. Sit with a treat in your hand and be patient. If your bunny doesn’t come to get the treat then leave the treat where you was sitting when you leave.
Rabbits hate being picked up! This is because they are prey animals and it makes them feel unsafe and vulnerable. It is always best to fuss & play with them while they are on the floor.
Bunnies are very clean animals so make sure their accommodation is clean too. If you wouldn’t like to sit or lay on what they sit or lay on then don’t expect it to be acceptable for your bunny.