I have open areas along both sides that I put my lines, muffs, PFD's, etc. They are about 5' long, 4" wide and 6" high. Big enough where things are not moving around.
I also tuck them into the seat cushions, and I flip the front fenders on the front deck, and one middle ones inside the side door. I also make sure that I have all the dock lines accounted for before I take off especially if some one is being helpful. I once docked for gas and the attendant untied the back of the boat and flipped the line on the back. It fell out and into the water and when I backed up at my dock it got caught in the prop and choked the motor. It cost me a spun prop hub and gave me a valuable lesson.
Mine are around 6 feet long so dropping them in a shelf or behind some thing is easy, and I never saw a need for them to be long enough to reach the prop, If i need a long line I use one of the anchor lines.
One of mine stays at the dock, The other gets stowed on the floor in the read. Out of the way and ready when needed. All other lines are stowed in a compartment with the anchor.