Hi tunisia_luva,
It won't be easy, I've looked into it myself, but where there's a will there's a way!
Unemployment in Tunisia is high, so it's very difficult for foreigners to get work, as technically it has to be proven that there's no suitable Tunisian applicant for the post (or so I've heard). Salaries can also be VERY low. An English woman I know got offered 220TND a month to work in a hotel shop - 7 days a week. Something else worth thinking about - the standard Tunisian working week is 6 days.
Rep work could be your best bet and the big tour operators might still be recruiting for this summer. It's very competitive (I went thorugh this all last year) and there's no guarantee they'll offer you Tunisia at the end of it, though they will ask where you'd like to be posted. (I got accepted as in-resort office staff with Mytravel but didn't go as they had no vacancies in Tunisia).
You could just save up a bit and go out there and approach the agencies directly in resort. Several reps get work this way, though it can be unreliable.
Another possibility could be to do a TEFL. It's not that common out there but certainly exists and could lead to teaching posts that would be better paid.
Good luck!