That depends if you want a correspondence/online program or traditional homeschooling. Generally correspondence/online programs closely match regular schools, except work is done at home. There isn't much flexibility. They provide all materials and you follow their schedule. Most people who do traditional homeschooling pick and choose among different curriculum companies to provide a customized education that meets their needs, interests, learning/teaching style, and budget.
I primarily use materials from Christian Light Education. They are mostly workbooks, which are pretty self explanatory and designed to be done fairly independently. I used to use Abeka (A Becca), but we found the work very dull and repetitive. Christian Light Education is academically sound and very affordable, but with more variety of activities in the lessons. They even have an accredited record keeping and academic advising service called Homeschool Plus you can enroll in for a nominal additional fee. I've been very happy with them.
Other good homeschool providers I've used are Sonlight (all subjects mostly literature based), Winter Promise (year long literature and activities based social studies themed courses), Math-U-See (math), Exploration Education (physics), Institute for Excellence in Writing (writing). Another good place to get curriculum, activities, and supplies online is Rainbow Resource.