I can't give advice on how to have a flexible mind, I just do. There are very few things, if any, that I have rigid, black and white views on. I guess I can see the pros and cons of most things, and that of course makes choices much more difficult. I'd say I'm probably on the opposite end of the spectrum as you, aquarius, as it's not uncommon for me to change my opinion on something multiple times a week (like, say, my thoughts on the philosophical value of black metal). I'd not recommend that, though, as it leads to quite a bit of mental tumult. Maybe the averages of my views will set with time, and I'll be a bit more stable in my beliefs.
I'd also like to second what crow said. If anything, it's rare that I consider myself to be correct.