Half and halve are not homophones, but they sound similar and their meanings are closely related.

Half:

• either of two equal or corresponding parts that together make up a whole
• the fraction equal to one divided by two

“I cut the pear in half”

Halve:

• to divide something into two equal, or nearly equal, parts
• to reduce by half

“I halved the pear”

My tip is to try to remember that halve is a verb. This advice is slightly complicated by the plural form of half – “I cut the pears into halves” – but the context should help you determine which is appropriate.