I shoot a new rifle (and an old one) from the bench resting the rifle on my hand rather than on a bag, and test various loads until I'm satisfied I have the optimum load. Then I adjust my sights to shoot centre with a centre hold. Most preliminary work is done at 25 yards, but I confirm my results at 50 yards with five shot groups. When I'm back in the the shop after cleaning the rifle, I stake both front and rear sights with a witness mark. This has saved my butt several times when I get to an event, check out my rifle, and find that one of the sights is not on the witness mark. A quick tap and stake returns the sight to it's proper windage position. I transfer the date to a page in my binder that lists everything vital to the load, ie: date, weather, range, rifle, ball and weight, patch, lube, powder and charge, etc. This data is transferred as neatly and precisely as I can so that I don't have to guess at what I wrote. Many of the targets posted in this thread would be no use to me as they are too much a clutter, and too variable a target. Although I sometimes save a target itself and file it with the data, usually I just make a facsimile on the data sheet by placing the target over the page, and put a dot in the centre of each hole in the target. I draw a line through the two holes of the five shot group that are the furthest apart, and two lines , vertical and horizontal through the holes that are furthest up and down, and left and right. Using a Vernier's caliper, I measure these distances and record that data with the copied target. As has been said, I record all targets I shoot, good and bad, so that I don't have to repeat something that didn't work, but I don't remember the details.
Having done this for years, one begins to see trends that assist you when you are starting out with a new rifle. These trends help you with a starting point and eliminate stuff that didn't work. It is unnecessary to re-invent the wheel every time you go to the range. Too, when someone asks a valid question about a load, you can answer the question based on your accumulated wealth of data. This should at the least, give the person a starting point.
Keeping complete neat records is key to getting the most accuracy and enjoyment out of one's equipment.