In skateboarding, What trucks would be the best for me?

I'm a street skateboarder, and however, My choices of brands are Thunder's, Independent, Venture, Destructo, or Krux. See, I can't ollie that well, but I know a lot about skateboarding. (I'm practicing ollies) I am going to 6th grade and I am 5 feet tall and I weigh estimately 127 was the last time I checked. When I get my ollies straight, I am going to do a lot of flip tricks and grind heck of a lot. So, What brand and what size of trucks should I get? (Sizes Low, Med, or High) 10 points when you help me fully.