I always make sure to take ubiquinol for cardiac support as just about all steroids are linked either to increased blood pressure, increased RBC count (which works the heart harder) or the potential for left ventricle hypertrophy, and ubiquinol (or at the very least ubiquinone the lesser form of CoQ10) is supposedly somewhat protective against that.

I don't take fish oil any more but do religiously eat oily fish 3-4 times per week, but would take the supplements for sure if i didn't like fish.

If taking deca, d'bol or (and especially) EQ, I'd also take a baby aspirin daily to help prevent excess clotting from the increased RBC count.

High strength B complex is a good idea too IMO, plus liver support of some kind, especially if orals are involved (either Milk Thistle, NAC or TUDCA).

Other than that it's the usual stuff I'd take whether on or off cycle - zinc, magnesium, creatine mono, and sometimes beta alanine.