I really want to grow spiritually and awaken psychic abilities (if I have any). So, I've been meditating. I've read about the information on Mediumship at Mystic Academy, but I don't know if I'm doing it right.

I don't know if I'm just imagining everything. Then, I started wondering if I have to be pure. I mean, what if I'm not pure enough to talk to spirit guides or anything? Maybe, that's why I'm not getting anywhere whenever I try to meditate and start imagining everything because my mind really wants to satisfy me and make me happy or something.

I strongly believe that our minds will hide or lie to us to protect us and to make us happy. But I don't know when it's lying to me.

I know I just recently began my search to grow spiritually, but there hasn't been any sign. So, I'm thinking that everything I've seen in my mind is because my mind is lying and that I might not be pure enough.

What should I do?  

"Patience Grasshopper"It will come.  
These things just take time.  Keep meditating.  Know that you are building a foundation to build upon.
As you pass various points of learning and practice, you will get more abilities.
Be patient, keep working what it is to be responsible. Meditate. Learn.

I never been the patient one. Maybe that's why I'm questioning many things right now.

But couldn't they give me a sign or anything to show me I am progressing? I mean, what if this whole time my mind was playing tricks on me?  

But still, what if I'm not pure enough? What if that's why I'm not advancing or something? Is purity an issue or a factor that controls the people's psychic abilities?

Depends on how you define purity and who's to say that what you (or anyone else) thinks is - is pure.
Do you mean like a boy scout - in word, in deed, in thought?
Look at the ages on here, have we lived pure lives? _ I think not.
Don't get stressed on this bit - there's loads of other bits that are far more important.

Well my wife thinks im pure alright  Purely full of sh*t .
I havent led a pure life or very spiritual one. but my power has gotten stronger thru meditation and training.
Cheers Pete