You can put an adverb of degree in front of a comparative adjective:
Examples: a bit, a great deal, a good deal, a little, a lot, much, rather, slightly
The potatoes are slightly more expensive than last year.
You can put an adverb of degree in front of a superlative adjective:
By far, easily, much, quite.
John is by far the most intelligent pupil in the school.
If you compare two things:
Susan is as tall as Carol
Karen is not as friendly as Kate.