Qigong is really meant to be practiced with no goal or expectation in mind, after all, when we have expectations, we can become disappointed. Daoism teaches us to release all expectations and to surrender to "The Dao" or the natural flow of things.
In reality though, most of us become interested in Qigong because of the positive benefits that natural result from the practice. It certainly improves our immune system, reduces stress, and allows us to be more spiritually aware.
However, this goal-oriented approach will not get you very far. The practice is very subtle, and only works when we let go of expectations of what we might achieve or feel. Click to learn how Chinese medicine treats Migraine.
The correct way to practice is to not expect anything special to happen; simply be open to all possibilities and listen to the feedback your bodies gives you. 4000+ years of Chinese practice has proven that if one practices like this, great things will happen automatically, it's just the nature of things.
Another reason you don't want to have expectations during your practice is that expectations can be limiting. If I tell you that Qi should feel like when you practice, then you'll be looking for that feeling, and might miss out on a more subtle senstation that I didn't tell you about. You also might have a slightly different senstation based on your body type, state of health or state of mind. But...if you simply let go, stay open to all possibilities and practice with proper posture, breathing and mind state, you will discover the secrets.
Ultimately you must explore and experience the effects of Qigong for yourself, firsthand. Through patient and persistent practice, you will truly discover your inner nature and get in touch with realms of your existence you were never aware of. We all have that potential inside us, we just need to relax and unlock it.