The difficulty is that some buds are really hard to see because they are not very pronounced. The leaf scar is below the "line" that you see at each node. it also helps to go out and look at the cuttings when they are still on the tree, in the middle of the season. Then you can see how the branch and leaf, and fruit, and sometimes the bud all fit together, how they relate to each other, how they are oriented, so that you can better evaluate the cuttings when they are dormant; to see how the cutting came to look like it does.
Another trick is to let the cuttings age a little bit, maybe at something between frig and room temps, esp. with greener cuttings which have less distinct marks. When they are a little warmer, the bud will begin to swell a little bit, which makes it easier to see.