First of all I recommend to stay in a casa particular and give personally a tip to the staff working there. Everybody is in need of cash.
Cubans - old and young, men and women - are always happy with any kind of beauty products so shampoo, a good smelling soap, perfume, after shave is always appreciated. All electronics and especially smart phones, laptops - used or unused - are a "big gift". Textiles and sneakers from all the big brands are available now in dollarito shops for reasonable prices (that means prices like in the US or europe).

Sun glasses and flip flops (Havaianas) are for my taste a very nice gift.

Cubans will not beg for alms so better try to keep your face and the times that tourists were paying the jineteras with the shampoo stolen from the Habana Libre are over.