Some people learn best through visual stimulation, so if this is the case for you, think of ways to make the Spanish letters catch your eye. You can write each letter on a flash card in bright ink; on the opposite side of the card, you can write the pronunciation of each letter. Line the cards up on the floor in order and read each one aloud, trying to get the pronunciation correct. You can flip over the cards if you have trouble or forget the pronunciation of some letters.
Probably one of the first ways you learned the English alphabet was by singing the alphabet song. When you pair letters with song, you remember the rhythm, which will not only help you remember the letters, but the sound of the letters as well. You can create your own alphabet song, but if you're a beginner, it's probably easier to learn a song that has already been created. Spanish alphabet songs can be found online. Repeat these songs over and over in your head and out loud until you've mastered the alphabet.
A pangram is a sentence that uses all of the letters of a specific alphabet and it can be a useful way to remember all of those letters. The website Spanish Learning Hacks has come up with a pangram for the Spanish alphabet which not only contains each letter, but every possible pronunciation of each letter. Here it is: "La cigüeña gigante bebió ocho copas de whisky, más quince jarras llenas de fría cerveza rubia, y enseguida huyó en un taxi." The sentence means, "The giant stork drank eight glasses of whiskey, plus 15 full mugs of cold pale ale, and escaped in a taxi right away." Read the Spanish version of the sentence aloud as best you can and then consult the website's video to correct your mistakes.
Other learners acquire knowledge best by listening to others. If you're in this category, try visiting people who know the Spanish language and can repeat each letter aloud to you. Repeat the alphabet to these people and ask them if your pronunciation is correct. If you don't have access to Spanish speakers, use online resources such as the websites Spanish Spanish and Spanicity which provide digital audio pronunciations of each letter. Like you would with a live Spanish speaker, try mimicking the sound of each letter after you hear it.