I am playing Bach's English Suite in a minor, and am currently working on the Sarabande. I know it is a slow dance of Spanish origin, but not much else. What are some characteristics of the Sarabande?
Triple time is about the only stable thing about the sarabande. It started life as a Guatemalan/ Spanish/Arabian dance, with a rapid tempo, danced by women, and accompanied with castanets. It was regarded by some as risque and banned. Later the French took it on as a much more staid dance, still with the 3 feel, and it was accepted as a more genteel dance, at a slower tempo.
The origin of the Sarabande is dance associated with Palo Mayombe in Cuba. Sarabande comes from the Bantu word Nsala-Banda which, taken literally, means Begin the Spirit, perhaps a nod to spirit possession associated with the dance, or meaning to get wild. Nsala-Banda or alternatively Zarabanda is the name of the god (mpungu) of iron and war, for whom the music and dance is dedicated. The dance in this context is not a partner dance, but is very physical and "in your face". The rhythms and songs were part secular, part sacred, and associated with night time performances, ceremonies, and communal parties, as it is now.
Very little of what made the Zarabanda what it is survived interpretation through the Spanish musicians who were influenced by and who evolved the music for their sensibilities and experience. In Spain, the music maintained 12/8 meter, a quick pace and percussive accompaniment. It was cracked down on by royal decree in the 1500s, however, the music continued to be performed and continued its evolution as it journeyed and filtered through different cultures. The only thing that remains of the Zarabanda from its origins is a 3/4 time and an incidental syncopation with an accent on the second beat.
One characteristic of the sarabande is that normally the second beat is dotted. In 3/2 the pattern is half, dotted-half, quarter, repeat. Check out some of the early La Folia variations (Vivaldi?). Sometimes (rather common) there is a a two-measure pattern of: half, dotted-half, quarter; half-whole. The short-longish pattern in triple time seems to be most characteristic.
As others have pointed out, early sarabandes (not necessarily written down) were in a quick tempo while more modern versions are played slowly, Either should be fine if you are writing your own piece but some historical analysis should be done to see how Baroque and other composers wanted theirs played.