I'm having the same trouble...
I use a variety of techniques though:
- Angles close to 90 degrees: try to figure out whether the angle is above or below 90 and choose from there.
-Very acute angles: find the smallest angle (which is usually the most obvious) and the largest angle or cancel out answer choices based on the smallest angle then compare the larger angles
- Between acute and 90: Cone stacking technique (basically the pacman technique) I try to figure out which is the largest angle and if it will stack like a cone on top of the other angles, and start cancelling out other options based on that
- Obtuse angles: use reference lines that match up (ie parallel bases) and compare the other leg of the angle to try and figure out which one is largest and smallest
There in my opinion is no sure-fire way, but you just keep practicing and eventually I guess it comes to you.
Bootcamp has an Angle Ranking Generator that's very useful:
http://datbootcamp.com/classroom/perceptual-ability/angle-ranking-generator/
Chad's website has a couple hundred angles to go through as well:
*can't post the link, but it's under the PAT section of his quizzes*
When you get bored of those, the Eyeballing game is also fun to do
http://woodgears.ca/eyeball/
Goodluck! Hope this was helpful and I will be here trudging along trying to figure out those friggin angles like you