You should not play for real money until you have proven to yourself that you have learned the basic strategy inside and out; doing otherwise is a great way to lose your hard-earned money and ruin the game for yourself before you even get a chance to play well. Take yourself and your money seriously by both learning the strategy and subsequently confirming your skills.
A good way to practice blackjack is to use a computer or app that allows you to play in a simulated environment. Otherwise, you can set up a table at home and deal cards to yourself or have a friend or roommate deal for you. Do everything that you can to make it feel like you are playing a real game, and take note of any weaknesses in your play after each session. When you can comfortably play hundreds of hands without getting emotional or making any basic strategy mistakes, you are probably ready to play in a real casino with real money. If playing for real doesn’t go well, go back to practicing until you build your confidence back up.