In the past few years, INAF - Astronomical Observatory "G. S. Vaiana" of Palermo has paid attention to the development of preventive conservation projects for archival documents, bibliographic materials and scientific instruments deriving from its two centuries of research activity. In 2017, following a previous collaboration with the University of Palermo, some interventions focused on the assessment and re-housing of part of the historical archive took place. A new conservation/restoration project on the oldest core of the historical library has started in 2019 and is still ongoing. In 2019 a pilot project was also proposed for the scientific collections on display at the museum. A survey of the assets conditions is ongoing and a series of environmental monitoring campaigns has been started to evaluate the microclimate effects on the collections. A risk management approach has been adopted to assess collections care priorities and to plan timely solutions and sustainable long-term strategies. The present contribution reports on the results of these experimental projects and on the benefits of the preventive conservation practice in the management of the collections.