I did Spanish GCSE and came out with an A* so maybe I can give you some tips.
Orals - firstly, ask to speak to your teacher one-on-one and tell her you don't know the format. Get her to go through what you'll be expected to do and make sure you understand. You should also start speaking to friends of yours who do Spanish too in the language and try and translate TV programmes or adverts when you're bored.
Listening - watch Spanish films (I can recommend basically everything Pedro Almodovar has directed, in particular 'Hable Con Ella') and try having English subtitles on first then watch again when you're a bit more comfortable with the language and don't have any subtitles in English (you could put some Spanish subtitles on if you find reading easier but the point is to improve your listening). Also, use the BBC Mundo website to find news reports in Spanish to listen to. Words you don't understand you could look up and make a note of in your vocab book.
Reading - print off tons of articles from the internet in Spanish and read through once to try and get the gist of what it's about then go through highlighting words you're not sure of and look them up in the dictionary. You could make a list of new words you've found and stick it on your wall then practice covering up the definitions and seeing if you remember them.
Writing - practice papers, practice papers, practice papers! Just go through as many past papers as you can find and practice the writing bit and try and do it in your own time first, structuring your response and then eventually time yourself.
When you feel more confident with your vocab, grammar etc. then move onto practice papers and get your teacher to mark them. Good luck!