Ask first - the prisoner will tell you what the rules are. Magazine and newspapers subscriptions are much appreciated. Polaroid photographs can only be sent in if the black backing has been removed. Do not ever jeapordize a prisoner by sending in contraband of any sort - in federal prison this includes pictures that show genitalia. DON'T try sympathy or empathy.
Sympathy is out of place.
The first response a prisoner learns in order to survive imprisonment is to avoid any sense of feeling sorry for himself or herself. The prisoner doesn't want you to feel sorry either. Drug war prisoners see themselves a political prisoners, captives taken in a political War on Drugs. A POW, except one who has succumbed to the influence of brainwashing, knows that the act for which she or he has been charged is political. Not sympathy, then, but positive communication about the folly of the Drug War is the best foundation for a healthy relationship between you and the prisoner.