Collecting money from kids for club activities is an extremely serious business and must be handled in a businesslike manner. Don't dump everyone's money into an old shoebox without keeping any records and expect to remember later on who gave what and how the money's supposed to be spent.
Instead, buy a serviceable receipt book, which generally contains a few hundred pages of NCR (no carbon required) paper. Just press down hard while you write and the interaction of dry chemicals on the sheets of paper will produce an instant copy. Carefully fill out each receipt for each kid, then gently tear out the receipts along their perforations and distribute them. The copies left behind form a book with a record of all cash or checks paid and receipts given out.
If you want to be a bit more high tech, you can use your classroom computer to issue electronic receipts or e-receipts, which in this case simply means that you type receipt information when a kid pays you, then print the kid a receipt. Depending on your typing and computer skills, this may be much faster for you than writing by hand.
Each time you issue a receipt, immediately lock the money away in a small portable strongbox or safe, to which only you, as the adult in charge, possess the key or numeric combination or both. Put the safe away in a locked cupboard after all money has been collected. When the meeting eventually ends, unlock the cupboard and take the safe home.
One more thing: Remember that holding money for a specified purpose is a sacred trust, not to be violated, upon your honor. If you're collecting money to buy movie tickets, make certain you use the money to buy movie tickets. If you're collecting money to buy uniforms, make certain you buy uniforms. Don't do anything that might violate your students' trust.