Listen to singers you admire and pay attention to the way they sound. Since you're going solo, learning by example is the best way for you to acquire the right tone and diction for singing pop music.
Practice simple vocal exercises to make your vocal chords stronger and more flexible. Begin each of your singing sessions with a proper warm-up, and drink plenty of warm water or tea to keep your chords clean.
Learn the right way to breathe. Your shoulders shouldn't rise when you inhale. Instead, your belly should expand and your lungs should fill with air all the way down.
Allow your voice's natural tone and sound to shine through when you sing. Use popular singers as examples of good musical execution, but try not to hurt your voice by trying to imitate them exactly.
Sing as often as you can, but give your voice rest when it needs it.
Look online for free answers to specific questions you have about training your voice. Each perspn's voice is unique, but chances are that another singer has already tackled the problem you're facing.
Create your own style and stick with it. Great pop singers all have unique styles of singing.