You should give some more details on your hunt.
Guide or no guide?
What is your physical condition?
How much time and money do you have dedicated for the hunt?
Rifle or bow?
A good place to start your research is Home Page, Alaska Department of Fish and Game
There is a wealth of information about population numbers etc. Once you find which area you want to go to you can contact the wildlife biologist that works in that area for harvest numbers. They are generally pretty helpful.
Another great website is Alaska Outdoors Forums
A wealth of information on that website. Of course you still have to wade through the b.s. because there are a lot old timers who haven't hunted in decades but want to tell you where to go.
I am sure more will chime in but the cheapest and highest success for caribou is flying to Fairbanks, renting a car, driving to the N. Slope. From there you can do a fly in if you pre-schedule or bow hunt from the road or walk in five miles with a rifle or pre-schedule for a boat trip up to the Ivishak River.
For moose it won't be as simple or cheap. It would definitely be difficult to hunt both species on one trip but not impossible. People do it all the time. I would recommend a fly in hunt. I won't recommend exactly where but you might start researching a fly in leaving from kotzebue for a possible caribou/moose hunt. There are other great areas for moose on the west coast.