The most likely kind of work you will be able to find is teaching English, if you have Teaching English as a Foreign Language (TEFL) certification. If you’re in the UK, contact the British Council, or get in touch with language schools in the area where you want to teach as possible avenues of work.
Bar work is a possibility in the Algarve, particularly in Lagos; ask around. You can also try looking in the local English press for job ads.
If you’ve ever thought about living and working in Portugal, then why not teach English as a foreign language (TEFL)? It could be the key to funding your travels and experiencing new cultures in a totally new way. You don’t need teaching experience or even the ability to speak the local language – although you might learn it while you’re out there.