How do you invoke/connect to these two elements? I've heard of people saying you have to call upon it or connect to it in order to manipulate it. But How?
This is my answer to the element question. Take it out of your head, and look for it in the world around you. I would hope to see an affinity with every element. The phrase "water is my element" is somewhat confusing to me. What are you? Some soup?
So. Let's say you want to explore water. Have a bath. Enjoy how your body weight changes. Pour the water from hand to hand. Or listen to the shower beating on your head. Go to a river, see how life is supported by it. Dance in the rain in no clothes. Go to a stormy sea and absorb the power of crashing tides over you. Observe the subtle drop, and the powerful and destructive force. Drink water!
For Earth. Don't sit there meditating about it. Get dirty! Grow some plants, - food, herbs, flowers. Smell it's scent, breathe it into your being. See the life that is in the earth, - beetles, worms, centipedes. Observe the decomposition of life into fertile ground, for yet more life. Keep a compost heap. Eat food!
So, you see how it goes. After you have done that, then read about how our natures correspond with natural elements. Earth is our teacher, we are of the earth. Then, maybe, meditate about it.
I truly believe that you can manipulate elements. It takes a lot of training and practice but it is very possible. I am naturally a bit aerokinetic, I have and affinity to wind and when was little I would go into these weird little trances and I could 'pull' the wind.
I cannot do it as easily anymore but I can still sometimes go into those little trance moments and I just know how to do it.
Just study aerokinesis and hydrokinesis, it will take time and patience but it will be well worth it.