Like anywhere, cash is appreciated as a tip for taxi drivers or anyone who may help you out. But, if you want to bring gifts, aim for things that are expensive or difficult for Cubans to purchase. Cubans need many things from abroad, tobacco isn't one of them. As for things like tylenol, we usually bring whatever over-the-counter items that we might need for the trip and leave any unused items for the hotel maid to keep, give away or sell as they see fit. However, I think you'd get strange looks if you just walked up to people and gave them a bottle of tylenol.
Clothing on the other hand is generally appreciated. So, if you have some gently used items that you'd like to donate, take them along. Hotel maids get most of the donations because it is easier to leave them in the room with a note, but people like hotel gardeners are also generally grateful to accept clothing, ball caps, etc.. As for chocolate, remember that Cuba is hot, so it may just melt into a gooey mess.
As mentioned, always carry small packs of tissue since TP can be in short supply.
