Wow what a horrible guide.
Tightening the gear cable while in the highest front gear is very tough and will only hurt your fingers. I recommend putting the front dérailleur into the lowest gear and tightening it that way. This is much easier!
As for your specific problem, in all my experience you can never not get 'rubbing' (if by rubbing you mean the chain running through the dérailleur over hang and brushing it).
However, you will notice that the brushing varies depending on whether the back gears are high or low. Since this varies the angle at which the chain 'points' to the back gears.
So the solution:
Since you will always have brushing (a tiny bit at least), you just seek to minimise it. Put the back gears in the most used gear before tuning the front dérailleur.
For example on my touring bike I'm usually in my third highest gear at the back, unless going up hills or firing down them. So I tighten my front dérailleur cable while the back gear is as such, this means I only get front gear rubbing when the back gear is perhaps in the very low gears, thus causing the chain to 'go backwards' at a different angle.
If you want to spend a ridiculous ton of money on a fancy dérailleur you can mitigate this, but there's really no need.
For mountain bikes the most common gear back gear is the lower one. If you're not sure which you've used most, clean the cassette of a bike you've used well, and look at the wear on each cog.