A. Take her blood pressure twice a day to check for hypertension. Lithium does not typically cause hypertension. Monitoring blood pressure is not a primary concern for patients on lithium. B. Have her drug blood level checked every month. Regular monitoring of lithium blood levels is crucial to ensure therapeutic levels and avoid toxicity. Lithium has a narrow therapeutic window, and frequent monitoring helps in adjusting the dose to maintain safe and effective levels. C. Avoid aged cheese and red wine. This advice is relevant for patients taking MAOIs, not lithium. There is no need for patients on lithium to avoid these foods specifically. D. Examine her skin closely for eruptions. While skin eruptions can be a side effect of some medications, it is not a primary concern for patients on lithium. The focus should be on monitoring for signs of lithium toxicity and other common side effects like tremors, thyroid dysfunction, and renal impairment.