These tips apply to the supermarket.
Shopping carts and Baskets
Shopping carts are found chained up outside the supermarket and in the parking lot. They are freed by placing 10 CZK coin (or 5 CZK coin, or a similarly-shaped disc) in the slot at the top. No deposit is required for baskets. However, these are not supplied by every supermarket chain. Whether it's a cart or a basket, some conveyance for groceries seems culturally prescribed. Don't be surprised to see (mostly older) Czechs transporting a lone bag of rolls and a tub of yogurt to the check out in an otherwise empty shopping cart.
Beer, Wine and Spirits
The other receptacle you will pay a deposit for is the glass bottle - typically beer bottles (not wine), and some other glass bottles (mineral water). However, you get the deposit back when you return the bottle. The usual price is 3 CZK. This is not included in the price of the beverage. It is added at checkout. You also have to pay a deposit for the plastic crates. The 4x5 plastic ones are usually about 100 CZK.
Buying spirits depends on the store and the spirit. In some stores cheaper spirits will be available on the shelf, while expensive or stronger ones will be behind the counter.
Don't touch the food
When taking a loaf of unpackaged bread, it is customary to place the plastic bag over your hand while choosing. Also, whatever baked goods you handle you are expected to take. This does not apply to fruit.
Weigh fruit before hand
You usually weigh your own fruit and vegetables. There are pictures on most machines in case you're not yet up to the Czech vocabulary. If you forget, you'll be sent back to the machine with the order “Musíte to z vážit”.
Cheese and cold meats, if bought form the deli section, will be weighed for you. Many supermarkets still measure by decagrams (units of 10 grams), usually referred to as a 'deka'.