Cereals, once open, need to be resealed in an air tight container to keep fresh. Spices quickly loose their potency when left open to the air. Staples like rice, flour and cornmeal need to be air tight, and should come out of their 'store' container and be placed in an airtight container.
Start simple and learn to use the supplies available at the grocery store. Zippered bags are your friend. I do use plastic wrap for left overs but I do not consider it a food storage device. Before you go buying matching canisters and stacking containers, buy baggies and a basket to keep them in. If all of your weekly cereals are in a zippered bag in a basket, you will notice how efficient this method ii, almost immediately. Again, if you are using the things you buy within a week or so, there is no reason to go all canister crazy, as in this photo.
When you make the step to canisters or containers cruise the websites that make them. Glad makes plastic storage containers and offers all the plastic content information and how to use information you could ever need. Rubbermaid is the next step up from the plastic bag and now offers glass containers and produce savers. Remember too, there are many generic and competitive companies that produce these products.
Since these two companies are at the top of the US market in recognizability, their information is where you want to start and then find that quality in a lower priced product. The Dollar Tree offers produce saving bags and containers, but I recommend learning about the quality product before making a generic purchase.
These are the most basic food storage devices and the first steps in preparing to store food. Storage should be part of your every day activity. We shop for food. We bring home the food and put it in a cupboard or pantry. We prepare food to eat. Storing food was a step that was overlooked and a skill worth building. When you bring home the food from the store this week, inspect it. Ask the questions. Will I use this right away? How long will it keep? Is it in its best container? Will storing it in a bag or canister extend its life? How much of this do I use in a year?
Get in the habit of putting food away in it's best container and preserving it until you need it. Just cutting down on waste and cutting back on purchasing more product because your food went stale is a savings you can invest in more food storage.