There are three fundamental approaches: prevent further damage and leave ‘as is’; restore to original ‘showroom’ quality; restore for use accepting that there will be modifications and compromises in material and method.
The first is the most popular for several reasons: it is the least labour intensive, preserves the most historical information, and for those whose collections are investments is the least likely to reduce sale value because of the emphasis on ‘all original.” (Nobody collects the Irishman’s hammer) Often, however, this method means the object cannot be used.
The second trades the ‘personal’ historic information of the artifact for giving an accurate picture of what it looked like when it was created. This can be very useful, but also very disturbing: a Classical marble statue painted in the polychrome style is jarring. It is generally the most expensive in labour and material. It also has the serious pitfall that the restoration is always an interpretation. Get it wrong and not only is it wrong (while masquerading as ‘right’), but you have lost the historical information.
The last is least popular. It is an approach that presumes that the object doesn’t have to be locked away, can be used and should be used. My best example is an Oriental rug in everyday use in the house: I recently rewhipped the edges using matching colour wool, as my great-grandmother had done before me. This protected the edge cording and maintained the tension of the weave. Without doing that the rug would have had to have been taken out of use. In making the repair, however, I was forced to use a slightly different type of wool in a slightly different stitch. It is now a ‘repaired’ rug not an ‘all original’ rug. Price wise I am sure there is a difference, but on the other hand the rug is stabilized, can stay in use and can be enjoyed. In this method, interpretation is an accepted fact: I have continued the object’s story rather than stopping it or erasing it: the original weaver, my great-grandmother, and I have all contributed to the object.
Acair Fearann 
I strongly support the “keep the story alive and going” approach. I think there is so much to be gained/loved/appreciated in being able to look at an object with all it’s accumulated use and changes, and in doing so bring to mind all the people who have enjoyed it. It not only keeps the object alive, it keeps memories alive and stories continuing – and continuing stories are always the best – they have a future.
Exactly!
Thinking of “objects” (of which Esperanza has a sufficiency) leads me to the Land of Oz. Specifically the story in which Ozma and her crew get into the Gnome King’s Palace and are turned into knick-knacks. All green, of course (Ozma becoming, as I recall, a grasshopper). I’ve sometimes wondered if L. Frank Baum was thinking of the multiple rooms in Esperanza and the multiple objects therein when he wrote that. (I’ve also played with the idea that he was thinking of the light on the north lawn in the evening of a summer’s day when he described the Land of Twi in the Enchanted Island of Yew.) Very likely not – for both – but it makes a pleasant fantasy, and we do know he visited there!