It used to be a hard and fast rule that you didn't split infinitives: that is, you didn't put an adverb between the base form of the verb and the preceding to:
Split infinitive: He begged her to quickly come home.
Better: He begged her to come home quickly.
Split infinitive: The coach told the ballplayer to firmly grip the bat.
Better: The coach told the ballplayer to grip the bat firmly.
This is still controversial. Many authorities now agree that splitting infinitives is often acceptable. But if you work for someone who hates split infinitives, by all means don't split them!