Good advice for sure.
I try to choose a powder that the case will be close to full, or a slight compression load. You have to do some study to figure out which powder may do that best, for the calibre your shooting, and the velocitys you want. IMR4831 is a popular powder, as is IMR4064 and H4350. I currently use RL-22 for the -06, 7mm rem mag, and .300win mag. It may be a bit slow for the .270
I usually do loads right up to the max listed, for the bullet, primer, and powder, but as I get closer to max, I will step up the loads in .5 grain increments, always watching for pressure signs. As mentioned, in some loads, velocity will actually stall. This may have more to do with your particular rifle then the load itself.
For some reason I have found that groupings for my particular rifle, seem to get best usually a grain, or .5 grain, less then max.
Nothing was mentioned about bullet seating for maximum accuracy, but this can also effect how well your loads group. You may want to look into this aspect of reloading for accuracy. Basically it's tweeking the cartridge o.a.l. for your particular rifle.
Half the fun of rolling your own, is trying different loads, bullets, powders, and even primers. Stick with published load data, be safe, and have fun!
