Well, I started at the very beginning... still at season 5 (2nd doctor), but it's great fun. ^^

You can probably start at the beginning of any Doctors time in the role without much loss of understanding or anything.

I'd do the reboot first, then go back if it interests you enough.

I started with the Nineth Doctor reboot. It's not too good at the beginning, but it gets so much better from there.

The four 'jumping-on' points I've heard of are:

-All the way back with the First Doctor (there's some missing eps, though)

-Third Doctor (Everything after that point is available)

-Ninth Doctor (Start of the revived series)

-Eleventh Doctor (New Doctor/companions, doesn't have much in the way of plot threads carried over from Nine/Ten)

Personally, I started with Ninth, but if you want to get caught up Eleventh'd be a fine starting point.

I started with the ninth. But it gets better when David Tennant gets on stage.

I recommend the episode where they go to space.

This is why I feel so alienated by DW fans, because if I wanted to get up to date with everything, I'd have to sit through shows beginning in the 60s

Have to echo those who have said 9th Doctor. You could start with the 11th, but characters and moments make much more sense if you've seen the 10th Doctor, and the 10th only makes sense if you've seen the 9th.

If you have someone to explain plot points to you then you really could start anywhere, but if you don't, the 2005 revival is an excellent starting point.

9th doctor. I started with 10, but 9 really set the stage for everything that's to come and shouldn't be missed.

This is why I feel so alienated by DW fans, because if I wanted to get up to date with everything, I'd have to sit through shows beginning in the 60s

... and what's so bad about watching a fairly old show? O.o

I started at 9th

I started just with series 7, and I can understand almost everything really, but I really should go back and watch Eccleston and Tenant.

I'm just echoing the common sentiment here, but I too advise starting with the 9th Doctor (1st season of the 2005 reboot) and just going in order from there. I think it's fair to say that the old series is not actually required watching, though it's definitely worth going back and watching the show's classic roots later on if you get some time.

For people who are debating whether to start watching Doctor Who in the first place, I actually recommend that they try out Series 3, Episode 10, "Blink" first. Due to the nature of this episode (without going into details), it doesn't actually require much prior knowledge of the Doctor or other story arcs, and gives you a fairly good idea of what you're in for (as well as the fact that it's just such a brilliant episode).

Start at the 11th. Season 5 of the reboot, I think.

Disregard everything you're reading and start with the first series of the reboot (number nine).

Yeah, either start with Nine's tenure, or with the episode "Blink" to get you hooked on.