I mix with strong juices - pineapple should be good but if not carrot is always a winner here. Make sure they are pure juices (not 'juice drinks') with nothing added and not a 'no added sugar' type, as they contain sweeteners etc which aren't good.
Failing that, I have found that Critical Care masks the taste of any medication. Toast is a less healthy alternative but that can work too, but make sure you don't burn the toast as you don't want to feed carbon with meds. I've also used weetabix and oats, as they absorb the meds quickly.