When selecting a bank in Spain try and take the following points into consideration.
Location
Your closest branch may not necessarily be the most suitable. For example, it may not have English-speaking staff or an ATM service, though these services may be available at a branch in the next town. In smaller villages branches have extremely limited opening hours
Distribution
Try to choose a bank with a strong presence across Spain as most banks charge a commission for using ATMs that are not a part of their network; choosing a small regional bank with only a few local branches may make immediate access to banked money an expensive exercise. Some local banks may also opt out of pan-European international payment initiatives, meaning that international transfers would be more expensive to process.
English-speaking staff
Some banks have English-speaking staff at specific branches to help foreigners especially in expat frequented cities, Madrid, Barcelona, Valencia etc.
Telephone/Internet banking
Almost all banks in Spain now provide these services; some also provide them in English. There are a few that offer Internet-only banking services, although these are only available to Spanish residents.
Statements and other documentation
Some banks offer the option of receiving bank statements and other related paperwork in English or another language. It is also quite common for larger banks to let you opt out of paper statements in favour of accessing your account details online.
As is often the case in Spain, a personal relationship at a bank is really helpful for sorting out problems and for if you need to get anything non-standard done. Ask friends, colleagues or teachers if they can introduce you to a director or sub-director of a local branch; if you have an opportunity take advantage of it.