I feel like you might want to make sure you have all your bases covered and that you're not setting yourself up for desperation/exploitation. Its so important with other people where this is suspected, to fail and fail quickly and and as harmlessly as possible.

Letting a taker take even once just teaches them they can take and move on to the next victim. People need to prove themselves as trustworthy before giving them anything. Offer them something relatively small like buying lunch. If they don't hesitate to take it then they're takers. Someone who won't refuse at least twice has no qualms about taking for nothing. But I just don't associate with people enough to allow them the chance to even try.