I follow the possibly outdated (by reading the last two posts) Wheeler book from 1990ish.
5g cane sugar per litre.
Barrelling is something I feel is not well covered in many advice/how to etc as I think people get so bogged down in talking through the mash, boil ferment they do not have energy to go into barrelling too. (I will at this stage point out I only have 3 brews under my belt and others on here are far more knowledgable but I'll add I have never had a brew spoiled)
Here is my routine...
Remove tap and cap from the barrel and add Vaseline to the seals then screw the tap back into place. (On a new barrel I could not shift the tap so figured it was probably tight enough to not leak)
Sterilise the barrel (I like to use bruclens for this as it cleans and sterilises seeming to do a great job of dispelling the remaining scents of previous brews). Fitting the cap to get that sterile too.
You will also need to sterilise the tube that be used to transfer the beer to the barrel. Sling it in the barrel to get it wet then remove it so you can get it out easily once sterile (I use star san for this nowadays and if you get into brewing I recommend getting some to make a 2 min sterilising solution seems pricey but the dilution rates mean it lasts an age)
Oh if you are using an FV with a tap this wants cleaning and sterilising too (again star san is great for this)
Now while that sterilises get the kettle on.
Just as it becomes sterile weigh out the sugar (for a 25 litre brew I used 125g) in a mug then top up the mug with boiling water stirring it into a sugar solution.
When the barrel and pipe are clean and sterile I then tip the contents of the mug into the barrel.
Now fitting the pipe to my FV tap I lower it into the barrel (not touching the lower sections of the pipe) and begin the sometimes frustratingly difficult job of getting the pipe end under the surface of the liquid (this stops oxygen getting in the beer). Once this is done get the tap on and beer in. (If you're syphoning I am unsure on the best process for this).
Now cap it and if using an HB cylinder give it a blast of gas, wait a few mins (that boiled kettle should quickly get a cuppa on), now loosen the cap (releasing the lighter oxygen), now another short burst of gas and you're barrelled!
Clean up time!
Two weeks in the warm... then 1 week per abv in the cold and it is drinking time!
