I must confess this is something I have been struggling with as well. My oldest just turned 4, and around here that means he can be enrolled in a free public school preschool program, complete with free busing. Over the last year I have changed from "Of COURSE he's going" to "Uh, I think we'd rather not."
1.) So instead of preschool, my idea was to enroll him in a once-a-week Something, without mom and without his little sister. And he loves it. He's been going to story time once a week on his own for the last year - we live in a small town, so this means between 0 to 2 other kids and a grandmotherly lady who reads to him. He's also doing soccer (once a week. no games - just a bunch of kids running aimlessly on a field.). He loves these activities, and loves to tell us all about his amazing feats of bravery. I also just checked out The Well-Adjusted Child by Rachel Gathercole from the library, and have found it very useful on the idea of socialization and homeschooled children.
2.) My parents are public educators, and in their inner-city districts preschool came about because of the large number of children who were woefully unprepared for school - i.e., their parents didn't read to them, many didn't have regular meals, etc. etc. etc.. And until last year I worked full time, and for the professional set preschool is a way to make you feel like your kid is learning something, and not just in day care. Then these things take on a life of their own, you know?
In our local district they say the kids who went to preschool are far better prepared to the actual getting-used-to-the-school stuff - lunch, standing in line, etc. - than the kids who were at home. If this is important to you, it's something I'm sure you can have your kids practice/expose them to before they get into school.
I also hear the traditionally preschooled kindergartners are much better at knowing lower case letters than the "homeschooled" ones, who generally know only their capital letters. Again, in case this is important!
3.) I agree with Stacey B regarding the workbooks - if your kid loves them, great. But why invest a lot in something that they may not be ready for? My latest favorite site is http://www.dltk-teach.com/
. I have discovered my kid loves dot-to-dot after printing off a couple of these pages, and so I bought a giant dot-to-dot book that he does before dinner or after story time. He also loves sequencing stories, which I wouldn't have thought of doing without looking at that site, so now we've integrated that into our week.
I have a friend that swears by the Kumon books, but I haven't tried them yet myself. She's scanning in all of the pages so that she can reuse the ones her daughter likes best.
4.) And I again second Stacey B, though I am a year behind her. I'm using this year as a fake homeschool. This means I'm trying to have a schedule we stick to (it's loose! and includes laundry!), and I'm reading everything I can about homeschooling. I looked on the MDC forums and found Waldorf, Charlotte Mason and Classical Curriculum resonated with me the most, and so I'm taking time to read about all of these points of view.
So far we have incorporated Waldorf-y stuff into our day/week/month. We have a daily schedule (the time we do things don't matter, but the order does), and in general I'm trying to cut out my bad habits (like computer time during the day) and start better habits (spending an hour a weekend planning for the upcoming week - food, what art stuff we'll do, and what I need to make it happen). In the 3 weeks we've been doing this, I find that if I know what's coming next, everything goes much more smoothly.
I also second writing down what works and what doesn't. And if you get bored or she gets bored (for me, this means my 4 year old starts wreaking havoc on the Whole House), add something else. Music. Finger plays. More walks. More park time.
Oh and the blogs! I find this can lead to a spiral of time sucking. I have limited it now to 3 or 4 that I really like and which I check with frequency - I've found so many people usually link to other blogs that I still find plenty of new inspiration even in only looking at those few.
Anyway, good luck!