It is almost impossible to meet all the requirements set out in some job adverts. Do not be put off by this; if you meet most of them, do not hesitate to apply. Portuguese employers can be flexible on this matter.
Most applications require a covering letter and a CV (although the letter may be omitted if it is not explicitly requested). Prepare your CV in Portuguese if possible. It should be clear and short (no more than two pages) and adjusted to each application.
When applying by e-mail, include the covering letter directly in the body of the e-mail. Only the CV should be attached. Write short paragraphs, and avoid informal symbols and abbreviations commonly used in e-mail and text messages. If applying by post, the covering letter should be no longer than one A4 side and typed.
Take care to respect deadlines, particularly if you are applying from abroad. And aim to submit your application early, in order to participate from the beginning of the selection process and be sure that the company has not already chosen a candidate.
Spontaneous applications can be very useful. Many Portuguese companies will archive CVs they receive and look first through these when they have a vacancy, to save on the time and cost of placing adverts.