The word up may be the most versatile two-letter combination in the English language. While up may appear as a noun, a verb or an adjective, its most common uses are as an adverb or a preposition. Remember this axiom: Adverbs are mobile, and prepositions are not.
Here’s why: As a preposition, up is immovable; in the sentence ”We climbed up the corporate ladder,” up cannot logically be moved to any other place in the sentence. In that case, the preposition-up combination is a unit, and you can’t split it up.
Now consider this sentence, which features a verb-adverb combination: “We looked up the information.” In that case, up can be moved, as in “We looked the information up.” Because up functions as an adverb, you can move it away from the verb.
Following is a partial list of common verb-adverb combinations using up: add up, back up, brush up, call up, clean up, close up, finish up, fix up, follow up, give up, lock up, look up, open up, polish up, set up, shake up, shut up, sit up, speak up, stir up, think up, wake up, warm up, whip up, work up, write up.
When you use up as an adverb in those combinations, move up to suit your needs. Otherwise, if up is a preposition, don’t split the unit.
-Adapted from Writing Tips, www.grammar doctor.com.