Sam,
Its funny that you consider 200-300 ft. as being "real high". Most beginners have a fear of flying high because they think that the plane might fly away, or they fear that crashing from that height will do a lot more damage than crashing from a lower altitude. The truth is that both perceptions are wrong. If you are flying a plane that has a hobby-grade radio, as long as you can see the plane you can control it. Although the wind is usually stronger at high altitudes, if the wind wasn't too strong for you to safely take off and land, the plane should easily be able to overcome the wind, even at higher altitudes (the only exception would be 2-channel planes). As far as crashes, the great majority of crashes occur when the plane is too close to the ground, not giving the flyer enough time to make necessary corrections. Beginners need to think about what action to take before taking the action, so they need that much more time to recover from a mistake. The 200-300 ft. altitude should be your normal flying altitude. I would clasify under 50Ft. as dangerously low; 50-200ft. as low; 200-300ft. as normal altitude; 300-500ft. as high; and over 500ft. as very high. I have a 2-channel plane with a 5ft. wingspan (Wind Spirit) that I take up until it is barely visible ( about 1000 ft.) I then shut off the motor and let it glide until it's ready to land. The flights last about 25 minutes (I haven't learned how to use thermals yet) and are very relaxing.

Don't be afraid to take the plane up high. Its the best way to give you recovery room for learning tricks.