I have 2 properties that I rented for part of the year, and resided in part of the year. How do I allocate my deductions for mortgage interest?

For each property, you allocate the interest according the percentage of the year the property was used for each.  For example, let's you paid $6,000 in interest for property 1, and you lived in property for 4 months, and it was rented for 8 months.  You would allocate 66.6% of the interest ($4,000) to the rental, and 33% ($2,000) to personal.