Use proper grounding and short traces for the external crystal to reduce parasitic capacitance. See MSP430 32-kHz Crystal Oscillators for recommended layout guidelines.
Use specified bypass capacitors on DVCC, AVCC, and reference pins, if used.
Do not route any high-frequency signal close to an analog signal line. For example, keep digital switching signals such as PWM or JTAG signals away from the oscillator circuit.
Design in proper ESD level protection to protect the device from unintended high-voltage electrostatic discharge. See MSP430 System-Level ESD Considerations for guidelines.