Exemption of a in translation

Question

A grammer question: I have been a member of- he sido miembro del...Why there is no uno like in English - he sido uno miembro (this sentence is a mistake).

Answer

Hola Sivan
Your question is not tagging any lesson so I can't see the whole sentence used, but, we do sometimes omit the article when we are using that noun with a very general meaning. For example, someone could also say something like "Tengo casa en Madrid" instead of saying "Tengo una casa en Madrid" - with the first one you are being more general and the second a bit more specific. 
Saludos
Inma

Answer

So I understand that Spanish is flexible in this issue more than English (like in word order in sentence that is not flexible in English).

Answer

Hola Sivan
Yes, Spanish is more flexible in that respect, but I wouldn't take this as a strict rule. Sometimes the articles are necessary and there is no other option, for example with verb gustar:  Me gusta la paella y el vino. (you cannot drop the articles here at all)
Saludos
Inma