azzy,
Solo climbing is not bravery but skill and responsibility. You need to be able to rescue yourself. There was an instance a several years ago that a person from East Coast came to climb Shasta to raise some charity funds and due to new snowfall called for rescue because he did not feel like descending the mountain on his own.
Relaying on weather forecasts, climbers have got in troubles or even paid with their lives. The top of Mt Shasta (above Red Banks) is quite large and if you get caught around the summit by clouds or whiteout you may not be able to find the proper way back, no visibility, no footprints. But even with a perfect visibility sometimes people get confused and take the wrong way down.
High altitude sickness may bring discomfort or be even fatal or contribute to an accident. Mt Shasta is over 14,000f high.
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However, on a nice weekend you would never be solo on AG, unless climbing late in a day above Helen Lake. So fallow the majority of people. If they go back, you go back. Be aware at all times of clouds' shape and movement. They may appear from nowhere at almoast any time. There is usually a ranger over the weekend on this route who tries to prevent unnecessary unfavorable outcomes. If he tells you it's not safe to continue climbing, fallow his directions. Be aware of high altitude symptoms, but don't be obsessed with thinking about them. Make sure that at any time you can easily descend the mountain. Walking with crampons on snow is simple, climbing ice is different. Self arrest is not that difficult on not too steep slopes and this route is reasonable safe (compare to other) if you cannot quickly stop. Just don't injure yourself with your ice ax. Yes, practice self arrest whenever possible. (This is the only skill that may really save your live while sliding.) Take food which does not contain (much) water, anything that you think you might eat. Melt a lot of snow. You don't want to be thirsty. If you realize you have no adequate cloths for the weather, just go back. Stay warm and dry. Never rest if you feel cold because it will only get worse. Observe your body and environment, use your judgment and act accordingly. It seems that you've already done a lot of research. Now what you need is just the experience.
If you follow the "getting to the summit is optional, getting back is a must," you should be fine. Have a nice and safe climb.
Here is a weather video from a week ago on Mt Shasta, perhaps you've already seen it: http://youtu.be/LjFzBBoH8zY