Perfect your alternate picking and learn the classic Maiden gallop. The gallop is a series of sixteenths notes or even constant sixteenth notes. If you listen closely to the bass lines in Iron Maiden songs you will almost always here this gallop. The verses in "Hallowed Be Thy Name" are a slow example of the gallop. Use a metronome and start slow by picking a single string and move up in speed.
Practice playing power chords and changing between them quickly. The gallop is often played with power chords rather than on a single string. Using only downstrokes with your pick will build speed but you can also quickly alternate pick power chords. A common progression in Iron Maiden songs is E-D-C in power chords on the fifth string moving up the guitar neck.
Learn about musical harmony. Iron Maiden's melody-driven riffs are played by up to three guitarists playing different parts in harmony. This creates the very smooth and full tone in many of their songs. The harmonized parts are usually in diatonic, minor, or major thirds. Learning scales on your guitar will help with understanding harmony.
Study Iron Maiden guitar tabs or music books. Being a good musician is about practice and repetition. Try to learn your favorite Iron Maiden songs by slowly working through each part. If one part is difficult, play it slowly and gradually increase speed. You will build up muscle memory and be able to apply the same skills later. Keep everything fun by playing what you can along with songs. Its okay if you cannot play the solos or make it through the entire song.