What if I have some doubts?
It's OK and natural to have doubts. Islam is based on the fitrah (nature of mankind) and encourages questioning as long as it is sincere.
The first step is to do your research and ask knowledgable people and get answers to all your questions.
Once you've done satisfied your mind, you should pray to God that He may satisfy your heart.
In fact, Islam’s greatest gift to you is the ability to have a direct two-way relationship with God (Allah) without the need of a middleman.
And the greatest spiritual tool to create this relationship is prayer. In the Quran, God describes His closeness to us:
When my servant asks you about me, tell them that I am near I respond to the Prayer of one who prays when he calls upon Me.
How should I pray?
For a prayer to have any affect, it must come from the heart.
And you should feel as if God is right there and is listening to everything you are saying.
Do not think that God is weak. He is the Possessor of Great Powers. Whenever you will put your trust in Him, he will surely help you.
What language should I pray in?
Remember God is the ultimate Creator, and as such understands all languages. Therefore, pray in the language that can best express the feelings of your soul.
How do I know when I've prayed enough?
One of the surest ways to know if you've prayed enough is to pray day after day until you notice a change in your heart.
Does is it feel more at peace now than it did before you started praying?
This feeling is different for everyone. You will know it once you experience it.