I'm not sure how old your children are, or what subjects you are going to design on your own. For me and my older kids, I make a list of the goals I want them to reach, concepts I want to cover and writing assignment ideas. Once I have my goals set, I gather the resources I plan on using as the core of the curriculum and then build additional material into it as needed to meet the goals. This method works well for me for history and language arts. For math and science I buy a complete curriculum.
I agree with what Brooke wrote. Seem to be doing a lot of that this eve Anyway I would also add that I like to make sure we add in projects to do with what we are learning. Whether they are art or science related. And I use a lot of free online resources. Its amazing what lesson plans etc are already out there to help you.
Limit the time you are willing to spend - and I mean - just keep an eye on the clock - I can spend hours following one link after another. Now whilst this is good and can revel some very interesting results, the downside is I then tend to have a bad nights sleep wrestling with all the ideas I've found, worrying if the computer will do a restart in the middle of the night and I'll loose all the tabs I have open and I still have to get up at 6am to deal with the man and the children....so I feel lousy the next day..... So, moral is - set a limit and stick with it, bookmark it all, and revisit....making a paper list at the same time helps too - you get fed up with writing after a while and then you start putting down only the REAL things of interest rather than the would be nice ones... (She says with match sticks holding up her eyelids at 6.30am) lol - because she had a late night last night....
Remember that the curriculum is NOT set in stone. Make it work FOR YOU. And if you can't throw it out and try something that you CAN work with.
I agree with what was said above. Pick what you want to learn or want them to learn and go from there.
What I wish I had known: You will make a mistake. You will waste money buying a completely useless book or product or learning tool. Get used to it, accept it, and move on. And then you'll do it again!! LOL also, be prepared to absolutely love a curriculum, then find out your kids hate it. When you are prepared for these things, they arent so devastating. And I also second the idea of limiting your search time. Exhaustion makes you desperate to just pick something to get it over with. Also, learn your kid's learning styles!!