IF you don't ask a question, you don't get an answer.
Ok, here goes and I apologize but since you don't give your State I'm gonna ballpark this.
The FIRST thing you need to do is type in '(state name) homeschool laws' in that little google bar or whatever browser you use and start going thru ALL the info that comes up (yes it's ALOT)....I know this seems like a waste of time but trust me you will get more info then if you go to JUST hsdla.org(which only gives you a SUMMARY of each State).
Now here is what I can tell you for FACT: Alabama requires an Umbrella School (no Ifs, ands or buts); Virginia requires you to submitt a COPY of your High School Diploma, a basic curriculum list and an ANNUAL Letter of Intent to Homeschool; PA requires you to follow the curriculum and hours for each subject laid out for their School system (public or Private); Florida {where I am} only requires that you submitt a Letter of Intent to your LOCAL School Board (basically the area you are zoned for) and supply them with an Evaluation every year---in Florida if you homeschool THRU High School, the child(ren) are NOT required to take ANY normally State mandated tests other than the SATs which they need for College ( and yes this is current and CORRECT info straight from the School Board's mouth).
Curriculum concerns++++If you have a budget (and most of us do), there are a number of ways to go.......borrowed,free,cheap,$$$$ (personally I prefer the first 3). With borrowed materials, you run the risk of severly outdated materials, BUT it gives you a chance to see if it is a program you like (the library is a good place to start); Free is really good, on occassion you might get outdated materials but that is rare, simply google 'Free Homeschool' and you should find a ton (**I'll list some below**); Cheap is where you can find them either in Thrift Stores or online (try to avoid Ebay if you need curriculum that requires a Teacher Edition as they CAN NOT legally sell it anymore); Pre-packaged curriculum will cost you and in most cases can only be used ONE time, if you go this route you run the risk of spending money for a program that MIGHT NOT work for your particular child(ren), and if you have multiple ages/grades, well then I hope you've got DEEP pockets.
Invest in a GOOD printer/scanner/copier (Lexmark is good and the price is decent **in my opinion**), if the children are all close in age or grade level and you use workbooks and don't want to keep buying the same thing over and over, then the printer will come in handy as you can make multiple copies and reuse the book (Jr is going to 2nd grade and Kimmie is entering 1st, do you really want to REBUY that workbook that worked so well for Jr in 1st????)....this also helps if (and I suspect) all the families are doing this together but not related to each other (Mrs. Shepards children are in 1st grade and the Jones are in Kinder????) you all put in a kittie pool and buy what you need and pass it amongst yourselves. This theory works great for Co-ops too.
When your State holds it's TAX-FREE Back to school sale, that is a great time to load up on things you will need for the year (paper,pens,crayons,erasers, etc). You can find good grade approriate workbooks at your local bookstore in the children's section (up to 6th grade I believe) and if you ask them they will give you a Homeschool Discount card.
Here are some items I suggest you have to make the journey a little easier......these are for your child(ren)s portfolio and need to be kept for between 2-5 yrs and shown at a review at least once a year or on a 10-15 day WRITTEN notice.
1) A plastic LEGAL size file box (to store schoolwork in) (plastic for avoiding bugs and its easier to carry)
2) LEGAL sized file folders---label these for each subject (math,history,etc)---the legal size is easier on the artwork the little ones make.
3) Calendar----whichever size is easier for you (I use pocket)--this is for your Attendance---for the days you do school just circle, the days you don't just X----(in Fla we must have 180 days, PA is 185 days) field trips count as a school day so don't forget about those (even if you only go to the zoo, it counts).
4) ***here's where you choose what best works for you**** you need to put your lesson plans down and this can be in A Notebook, LessonPlan Book(available in office supply stores and SOME dollar stores) or Calendar (if you get a wall or desk size one)----basically you are going to write what you did on such and such a day and don't generalize (the kids fingerpainted----WRONG!!!!) Art:fingerpainted Farm Animals;Math-played Monopoly(yeah you CAN do that); Language: Made the Alphabet out of Bread(you might want to take pics for the portfolio); Gym--Ballet Class(yeah that counts too)-------if it helps them learn or teaches them something you can write it down, many times the people on the Homeschool Portfolio Review Committee are Homeschoolers too and can give you pointers. They will also let you know if your records need to be more precise, too much info or not enough (in which case you just have to return in a set amount of days).
I am an ex-Preschool Teacher so it is easier for me to just write a lesson planbook up a month at a time (I can chunk a particular day if I need too), I also keep a spiralbound notebook listing ALL the materials I use (book list, curriculum list,computer programs,etc) ***I started doing that because I got sick of the committee saying "Well you don't have the books she's read" or "What math program are you useing?", it's easier to write all down and add on as needed and it SHUT'S THEM UP really quick :p***
5)Invest in a camera (digitals good even a cheap one) (throw-aways can get $$$$), keep it with you at all times (along with fresh batteries :) )---for those things you do like field trips or art projects that won't hold well or are too big for the portfolio because the saying "A picture says a thousand words" is pretty much on the money for homeschoolers (remember the Bread Alphabet idea??).
Here are the sites I promised you:(I'm not bothering putting www. in front of each):
OBDK.com(science);krampf@aol.com(has a yahoo group--science);homeschooltracker.com;oldfashionededucation.com(also has a yahoo group--free curriculum);crayola.com(art);lessonplanet.com;bookadventure.com;audiobooksforfree.com;kidswings.com;spellingtime.com(down till august to clear the system);christianpreschoolprintables.com;trendyteachers.com;escapefromknab.com(learning game);missmaggie.org(Maggies Earth Adventure);learningplanet.com;playkidsgames.com(math,vocab,geography);dryiceinfo.com(science)+west.net;freeworksheets.com;wxdude.com(weather);makingfriends.com
and two Homeschool Magazines to check out: This Old SchoolHouse and Practical Homeschooling.
I hope all of this helps you in your journey.
I ALMOST forgot this little tidbit: Should Child Services OR a Truant Officer come to your home, you DO NOT have to let them in UNLESS they have a Court Order. You simply inform them that you homeschool and refer them to the SchoolBoard Homeschool Education Office (give them a name and number if you can) or (now this will cost you $$$) either have an Attorney on standby that you can call or call the HomeSchool Defense Legal Association (HSDLA) and they will take care of it. Again I say you DO NOT, DO NOT have to let them in and they CAN NOT under any circumstance talk to your child(ren) without a LEGAL GUARDIAN present. *****This is a little know fact/loophole. I like to call it my ACE IN A HOLE for those times when you get people (friends,relatives,nosey neighbors) who just LOVE to make trouble.******