When I first started this hobby many many years ago, my buddy who introduced me to 40k had this little rule that we used to make it easier for me to make a list as a beginner. We use to call it the three point rule, where you were able to take three points above the selected agreed points level!
Obviously, I wouldn't expect anyone to be over the points in a tournament environment, but how about in a pick up game or a game with your buddies? Would you mind your opponent being a few points over? How would you deal with it? Not play them? Get them to drop a piece of wargear? Take something in your list to take you to the same points? Or wouldn't you be bothered and just play?