Not going into specifics on cuttlefish husbandry; water quality is of key importance, which will be incredibly difficult if not impossible to maintain in a tank of only 30 gallons, not to mention that that is far too small for S. officinalis...adults of this species reach mantle lengths of nearly half a meter and would need a 150-200 gallon tank at minimum!
Keeping the species at home is not impossible, and husbandry practices in public aquaria are far from rocket science, but it will require a good setup, large tank, soft substrate, a highly varied seafood diet, attention to detail, and EXCELLENT water quality. Also consider that if you are getting small juveniles, you will ideally need to have a large supply of live food (mysid shrimps/other small shrimps depending on size). Check the TONMO site for more info, and here are a few references:
Wood J.B. 1998. Cuttlefish husbandry part IV. Aquarium. 21 (10) : pp.64-66
Wood J.B. 1998. Cuttlefish husbandry part III. Aquarium. 21 (9) : pp.78-84
Wood J.B. 1998. Cuttlefish husbandry part II. Aquarium. 21 (8) : pp.72-78
Wood J.B. 1998. Cuttlefish husbandry part I. Aquarium. 21 (7) : pp.72-74
Anderson R.C. 1987. Cephalopods at the Seattle Aquarium. Int. Zoo Yb.. 26 : pp.41-48
Choe S. 1966. On the eggs, rearing, habits of the fry and growth of some Cephalopoda. Bulletin of Marine Science. 16 (2) : pp.330-348
Domingues P.M., Kingston T., Sykes A. and J.P. Andrade 2001. Growth of young cuttlefish, Sepia officinalis (Linnaeus 1758) at the upper end of the biological distribution temperature range. Aquaculture International. 32 : pp.923-930
Domingues P.M., Sykes A. and J.P. Andrade 2001. The use of Artemia sp. or mysids as food source for hatchlings of the cuttlefish Sepia officinalis L.); effects on growth and survival throughout the life cycle. Aquaculture International. 9 : pp.319-331
Koueta N., Bouchaud-Camou E. and B. Noel 2002. Effect of enriched natural diet on survival and growth of juvenile cuttlefish Sepia officinalis L.. Aquaculture. 203 : pp.293-310