I wish Chris Farley were still alive. Like...Samwise looks like a skinnier Chris Farley. There would have had to have been some amazing spoof videos in that universe.
And throw it around to the side, not over the shoulder.
Up-and-over can drip all kinds of flaming liquid over you should the container not be sealed properly.
Out-and-around/sidearm flings it to the side.
Make sure you have the clearance to the side and nobody is in the literal line of fire, and you're good to lob your cocktail at the spot you intend to hit.
Super lpt: get a lacrosse stick, become proficient with it.
Super duper lpt: don't shove the burning rag into the bottle. Seal the bottle with whatever normally seals it, then tie the rag around the neck. The idea of a molotov is that the glass bursts open first upon hitting the ground, then the flammable substance catches fire from the rag. Since the bottle needs to break anyway, shoving the rag inside of the bottle is unnecessary and dangerous.