Dear Little Princess,
Right now, your spiritual life consists of saying "I wuv you, Zhezus!"and splashing about in holy water fonts. (You also enthusiastically kiss my Divine Mercy medal whenever you get ahold of it, which hurts my neck a bit but melts my heart quite a lot.) Since you're only three, that's pretty good. When you get older I'll introduce you to some new people: Ignatius and Irenaeus and Augustine and Bernard and Bonaventure and Thomas Aquinas and Julian of Norwich and all the other names I can't remember right now that are currently in boxes in my closet. But that's for later. After you learn to say all your consonants properly.
You'll find, I think, that God is awesome beyond all telling. Everything I can tell you about Him, everything you'll hear and read about in the years to come, only touches the fringes of the reality. Then when you get to Heaven (I pray that you do get there), you can spend all of eternity with Him, soaking up more and more awesomeness and still never getting to the end of it.
Of course, this isn't Heaven down here. There will probably be days when God doesn't seem so awesome. You'll probably wonder what He's thinking with all the crazy things you have to go through, all the prayers that seemingly go unanswered. When it feels like that, just remember that, as we celebrated yesterday, God is with us. He was born, which is messy enough, in a stable, which is even messier, and laid in a manger, on prickly straw, with smelly animals all around. When your life stinks, just remember that. God can come to that place too.
If I could sum up my advice to you in a few words, it would be this: Remember that you are never alone.
And remember always that you are loved.
With all my love,