LGA parts and hot air soldering
First of all, if you are using lead-free solder, it sucks, if possible use leaded solder. 

There are two categories of soldering. With interaction and without. Interaction refers to the necessity of having to touch the chip in any way during soldering. 

The only way to solder a chip like this without interaction is to use a stencil and solder paste. The stencil dispenses the correct amount of paste. Most importantly the paste is even on all pads. It also almost eliminates solder bridging because the stencil separates the paste on the pads. It looks like you have a single side load. In a case like that, I like to heat the board from underneath, it keeps little chips from blowing away. If you can't do that, then heating from the top is ok but requires a bit more caution. The even solder paste pays off because the chip sits down evenly. 

The way I suspect you are soldering the chip is that you apply a strip of solder paste on each side of the chip and then letting the surface tension pull the solder into place. This type of soldering will require intervention. Dispensing just the correct amount of paste is nearly impossible. The tendency is that too much is put on.  This causes shorts that need cleaned up after wards. Also, it's suggested that once the solder paste melts, make sure the chip is positioned and then hold the chip down with tweezers and remove the heat. Hold the chip with the tweezers until the solder cools. This will force out any extra solder from under the chip keeping the chip from being crooked. Finally, use a soldering iron with a small tip or knife tip to clean up any solder shorts. Be sure to add flux before removing the shorts. 

Another method is similar to above but tin the pads first instead of using paste. Make sure to add a generous amount of flux before putting the chip down.