I think you will do fine making your first loads for this rifle. You asked the procedure with powder charges and seating depth.
This is what I suggest: Choose the seating depth that will fit and feed from the magazine AND not touch the rifling. You might want to take some of your shortest cases and make a few dummy rounds to test the feeding. After you have established a workable COAL (cartridge overall length) then make a series of 4-6 loaded cases with different powder charges. I think for this size case 1 grain increments will be fine. Start low and work up to the highest powder suggested by a loading book like Nosler's or the powder manufacturer's data.
If you are not happy with the groups size you could alter seating depth. Take the tightest group and make more loaded ammo with bullets seated more deeply in .005 increments. This is a real pain if you don't have a competition seating die. It doesn't always work but generally as you shoot incrementally deeper seated bullets you may begin to see a trend in groups size. I would think you would begin to see the group size change within 5 or 6 seating depth increments. Once you find a better shooting seating depth you must be able to set the seating die to that depth accurately. If you don't have a bullet seating depth comparator or similar device you are wasting your time. You can make one or buy one but it would be essential to making accurate seating depths as well as later when you setup your seating die in the future.
Two versions of comparators:
You could make one of these: http://www.sinclairintl.com/reloadin...prod34262.aspx
You need a drill size a few thousandths smaller than .308".
It wasn't mentioned but your rifle should be sound. The action screws should be tight, as should the scope rings and bases. Barrel should be clean. Then your load work up won't be tainted by performance issues caused by the rifle.
Good shooting! Come back and share your results.