I learned to use a linoleum knife in the garden from my mother, who had learned it from her father. It is a handy tool for grass edging, weed removal, digging rocks out, and many other things. It makes quick work out of even the weediest garden. You definitely need to give it a try!
After it rains a good rain, try edging. It is a whole lot easier for the shovel to go in and a heck of a lot easier to lift the excess out of the ground.
To save time and money trimming and edging the grass along your sidewalks and driveway, simply drop one side of the the wheels on your walk behind lawnmower mower all the way down until that side barely touches the solid surface of your sidewalk/driveway.