Perspective of a Homeschooled student:
Homeschooling has been a great boon to me. I can't really say how great, since I don't really have any perspective on High School (my last year of conventional school was seventh grade). When I was talking to my local guidance councilor during the college application process (something that really needs to be done, since these councilors are the only people who can really help you deal with a lot of the paperwork) he was constantly amazed that I had done what I considered routine measures. He once commented to my mom that he was amazed how prepared I was, and that he wished that every student he saw was as prepared.
Why is this? Well, you try and kick yourself to get work done every day. Many people have to have that taught to them by college, or life, not during their teenage years. And yet that's when you have the easiest work! It's really done wonders for my schooling.
Dealing with the subjects:
Math
Math is a subject that you're almost definately going to have to "farm out" after a while. One of the worst mistakes I see homeschooling parents making is trying to teach their kids math past the level in which they ceased to understand it. IE if you struggled in Algebra, then find someone to teach your child Algebra. The quickest way to make someone fail in math is to expose them to your own insecurities in dealing with it. I was fortunate to have a great teacher - a former Villanova Physics professor - who taught me right through calculus. He taught a lot of homeschoolers in the Devon area (though he's had to go back into engineering since teaching didn't pay well enough

).
Science
Pre-High School science is easy. Just buy a textbook, and make sure you're always a chapter ahead. Heck, most of the homeschoolers I knew could handle it without much guidance. You may want to introduce a lot of the High School concepts early, as I feel that a lot of time is wasted on somewhat ridiculous projects (yeah baking soda and vinegar make bubbles, but the third time you see this you should be learning that the H+ and the OH- ions are interacting to form water, leaving an inert salt and a gas byproduct).
At High school level it changes.
Physics is another subject that you should farm out unless you have a great understanding of it. Calculus is necessary for large portions of it. Be careful that you don't fall into the school's trap of teaching the equations not the concepts. A lot of school taught people can recite the resistance equations, inertia equations, everything in physics, and have no idea why this is the case.
Chemistry is something that you basically need to farm out. I personally love it, since it is simple, low math, and perfectly logical, but I know a lot of people don't feel that way, and certainly don't have time to learn the valences, etc. needed. Please don't turn chemistry into rote memorization of the periodic table. As my professor said (the same one who taught me math) "You want to know the periodic table? Open the front cover of your book. Don't bother with memorizing it. There's never going to be an emergancy situation where you say 'Oh, if only I'd memorized the periodic table I'd know what to do.' You can always look it up."
Biology is a touchy subject, I know, so I'll leave it alone. My mom personally had no problem with evolution, but I'm well aware that she's not completely representative of the population. My suggestion if you really hate evolution is to teach your child both sides of the issue and let them decide. You could even let him or her participate or just start a debate on evolution on this site. That should give them a somewhat balanced view of the issues, and would certainly expose them to the debate (I personally feel that it's settled, but whatever).
Writing
I was fortunate enough to have a mother who worked for the Baltimore Sun and is a very good writer to teach me. I would say look for a writing course with someone like her, but I think she's one in a million. Honestly most of the stuff I see coming out of the High Schools is pure trash by my standards, and by hers. Remember to emphasize the art of the essay. The essay is certainly the most important part of writing. Grammer and spelling are nothing more than rote memorization activities, that help the schools out a lot when they need to look unbiased in their grading, but do little to enhance writing itself. I have seen stuff with frighteningly correct grammer that is pure trash. Unfortunately a lot of this seems to come from homeschoolers who have parents that overemphasize wordly wise. Try to do a lot of creative writing style essays, where the child is assigned to write an essay on virtually any subject. Good ones that I remember was a newspaper article on a martian landing, favorite bubble gum colors - good for younger kids, and the old "pick a topic and write an essay on it." Those really build essay writing skills, since the subject matter is almost a non-issue. Instead you and the child can focus on the construction and layout of the essay instead of the subject matter.
History
Don't do pure textbooks please. There is nothing more boring then reading about every explorer ever to hit the coast. What a waste of time. Honestly I see very little bias in the textbooks towards either liberalism or conservatism. Instead I see that decades of lazy writers have shielded their poor work behind the mantra of "Political correctness forced us to do this." I'm sorry, but no political correctness issue forces them to reprint every man who took a shine to visiting America.
Instead I would recommend history be taken in parts. Have your child read a section of the history textbook, then study some part of it that was of interest to him. Probably the best idea would be to find some college lectures on tape, and show them to him or her. I saw some utterly brilliant ones that my mom got on American History that I had unfortunately already covered. The gain of knowledge didn't outweigh the pain of covering the Pilgrims for the zillionth time. Don't let your kids fall into that trap, expose them to interesting history early on.
Anyway, that's my perspective and advice. It's a little long, but if you're going into this looking to avoid long reading... Good Luck, and remember you're doing what's best for your child's future.