Keep in mind that I am a telecommunications lineman looking to go power and get an apprenticeship. I only took the telecommunications lineman position to gain construction experience. From what I have gathered through interviews and those in the trade is:
1) Sign your local union books to be a groundman. Apply for entry level positions at power companies near by. Many power companies will hire within for apprentice lineman positions. But check it out to make sure. Also get any and every cert/license you can that helps you. The first of these to get should be your Class A license. I have a permit and have yet to get my license. I wish I had gotten that taken care of already but unfortunately I haven't. I have an appointment with the DMV and will finally get that taken care of.
Get your First Aid/CPR cert, OSHA 10, Flagger cert, and heavy equipment certs (crane operating). Some say the crane operating cert is a waste of time but it may be enough to push you past other applicants. All this really doesn't help with any lineman experience but it shows the employer and interview panel that you are doing what you can. It shows you are determined. If you can go to lineman school, do that too. Almost any lineman will tell you it doesn't really teach squat but it does get your feet wet and shows the employer you want to be in that trade. Also, some power companies require line school. If I could do it, I would. I would have been hired by Edison as a groundman with the climbing school (got a job offer because they thought I went to line school. When I told them I didn't go to line school they said " Sorry, thats what we look for".)
2) What I have herd from others that went through an apprenticeship is that school is school. Bookwork is bookwork. Don't expect it to be any different than taking a college level class. If you do what is necessary and can do basic math, you should be ok, again from what I am told. And please, If I am wrong, anyone that knows, correct me. I have been told it can be tough with all the work you do but your will to want to do this job will override the bookwork.
3) I think number 1 answered number 3. Try the books. Try your local power company. Also apply to JATC apprenticeships. Be willing to travel. I am willing to travel to another JATC to get my foot in the door. I think most of those who really want to be a power lineman are willing to do the same.