You'd be insane to mix it yourself...
Around here, there are 2 or 3 different cement companies I can call to have it mixed and delivered to me... I'd just need to know how many yards to order. (A yard meaning a cubic yard.) You select the type of mix you want; it's quite inexpensive - you'd be a fool to mix it yourself. They'll simply deliver it to you at the time you want it, and pour it out a chute onto your job site (or, if the job site is inaccesible, you'll have to quickly transport it with a team of guys with wheelbarrows) It's back-breaking work especially if you don't have the right tools and machinery... Pouring and finishing the concrete is the easiest part of the job though (in my opinion)... it's all the prep work that's difficult.
You could probably do it yourself if you spent 2 or 3 days watching a couple of driveways getting done. Personally, I've been debating doing it myself one of these years or just getting a blacktop driveway.... or perhaps going the more difficult route and putting down really nice pavers or having stamped concrete done. Someone above said to hire it done and it'll be done in one day?? Must be a really small drive-way to do in one day. Usually, the first day is prep, the second is pouring and finishing. The 3rd (not necessarily consecutive) - removing the forms and finishing around the edges (dirt, etc.)