Here is my procedure that I follow whenever I get a new rifle and start looking for a load.
1. Make sure that the scope mounts, rings, and scope are all locked down completely solid.
2. Use some Wipeout, Butch's Bore shine, in mulitiple rounds of barrel cleaning to make sure all the copper fouling is completely gone from the bore before I start.
3. Depending on bore twist, read, ask around to find a bullet that has a reputation for accuracy in that cartridge. Normally, I look for a Sierra bullet, they have always worked for me and don't cost a fortune. Typically, I find it is one of the heavier bullets listed in the load manuals for my cartridge. Probably not the very heaviest, but fairly heavy. For a 25-06, I know a good popular bulet weight is 117 gr, so I would start there.
4. Then I would pick a powder that is towards the slower burning listed for that cartridge and bullet weight. It doesn't have to be the very slowest, but you want to get the case pretty close to full. For a 25-06, I would probably try something like H-4831 or IMR-7828 or Alliant RL-22 to start with.
5. Go to the powder manufacturer website or your reloader manual and find the max charge weight listed for your bullet/charge weight. For example, suppose you were going to use a 117 gr bullet ant H-4831, and you read that the max powder is 52.0 gr of powder. Now, subtact 10% of that powder weight. That gives you around 47.0 gr as a starting powder charge.
6. Load up 3 cases with 47.0, 3 cases with 47.5, 3 cases with 48,0, etc, varying each set by 0.5 gr, which is 1% of your max until you have 10 sets of 3 cartridges ranging from 47.0 up to 52.0 gr. Make sure you mark each case to make sure you know what they are loaded with. Pick a bullet seating depth that is recommended in the manual and keep it the same for all the loads.
7. Take 10 targets to the range. Starting with the 47.0 gr charge, fire 1 round from each different set into each of the 10 targets. Pay attention to each shot, noting if you encounter a bolt that is hard to lift, or anything out of the ordinary. If you find a shot that is hard to extract the case, stop there, you have found your max charge weight for your rifle.
8. When you have shot each target one time, allowing the barrel to cool after 3-4 shots, going from the lightest charge to the heaviest, start all over again and shoot each target one time with the appropriate charge weight.
9. When you have finished, you will have 10 targets with 3 holes in them. Look at each target and the overall trends carefully. Of course you are looking for any that have a tighter group. But you are also looking for trends where the group sizes look similar and the average point of impact is about the same. Those are the accuracy nodes you want to focus on.
10. Focus on those groups where accuracy was the best. You might want to tighten up the interval to 0.3 gr and load 5 or more loads centered around that magic charge weight. If there's nothing wrong with the rifle, then you will definitely have a nice shooting load. You can try different bullets, different powders, but you need to go through thihs exercise each time you change one variable.