Welcome to the forum. You have just joined a great hobby. The people here will be a lot of help but the old threads have a lot of hidden info. Read through some of them or enter a subject in the "search engine" above and it will find that subject for you.
I read once that if things could serve 2 purposes than that helps with the storage. What do you use most in the house kitchen, bathroom? Can you pre-make food items? Spaghetti, ribs, mac and cheese, potato salad and reheat what needs heating for your weekend trip and keep rest refrigerated.
Get a collapsable laundry bag, or use a pillow case. If inside space is tight, use basement space for non-perishables (TP, paper towels, napkins) if going on a extended trip. Blankets that double as throw for the couch. Collapsable chairs, Plastic dishes that work in the microwave instead of glass keep the weight down.
Rv's in general usually have every available inch of space worked out for storage but if you need more and can add a shelf, do so. Spend a bit of time inside it in your driveway to see if you can cook and whatever and don't need to run in a keep getting items to cook with.
You'll figure it out. Took us a while but we have it pretty good right now. Might change as we go on longer trips but we have plenty of empty compartments right now so still have room and weight we can add.
Go into a camping store and look at the items. Most are less expensive elsewhere, but they have all the useful items close at hand at camping stores.
Good luck and enjoy your rig. Lynne
Retired January 4th, 2018 Lynne & Jerry RVM 105
04 WBGO Itasca Sunova (Miss May) Blue Ox Tow Bar
15 Equinox (Noxi) 18 RAD Mini e-bike, 04 Tracker