Adding shelves to your storage shed would just increase the efficiency and use of your shed. Pitch is slope or angle from wall plate to the roof ridge line. Once the board is cut to that measurement, check the fit and adjust if needed. Add wall backing to any tub and faucet inlet areas and wall-hung appliance locations. Cut gable top plates to fit diagonally against ridge beam. Based on the design you select, it can provide shelter from the rain as well as other weather conditions to allow you to continue with your gardening in peace. Adding drip edge and felt paper to your roof before putting (https://shedconstructionplans.com/gambrel-hip-roof-shed-plans-list) down shingles is definitely an option.
For a concrete slab, measure diagonally across opposite corners of form boards. Once firm and dry base is now ready for you to begin assembly of your garden building. Some online sources offer different blueprints for storage and backyard sheds. Small cracks, knots and color tone differences are not errors but inherent qualities of wood. Now take last 2×4 for frame of the shelf and mark where each brace will sit on the board. Brace them in place both directions. Add blocking between each rafter every 4 feet to support the edges of sheathing and to prevent rafters from twisting under snow load.
If you have a wooden shed, whether old or new, a bright coat of paint on the interior could extend its life as well as give you reason to spend time there. Place window frame on wall in such a way that its edges are square with edges of the wall boundary. Rain screen spacer mats provide another method of creating a vented airspace. The shelf needs to end on a stud to attach this brace. You do not have to worry nearly as much about bad weather ruining backyard outbuilding and causing it to slowly fall apart. Then do same thing at the top of walls, and finally when you set roof trusses or ridge.