A bit ironic seeing as my last post mentioned my lack of motivation but hey ho. Sorry, this is a ridiculously boring subject but if someone told me these tips before I started 6th form I reckon my grades would be completely different. I really do not what the same thing to happen to you so here we go.
1. Past Papers- I know what you're thinking "I'll only end up revising what is on those papers, instead focusing on what could be asked generally", I was exactly the same. I thought I should know the basics before I even looked at past papers, until I actually tried it.
2. Que Cards- I used to think they were useless too! Until I found out that I was writing down the wrong things. I tried writing down the correct answers from the mark scheme once I got a question wrong but phrasing the question in a more general way and it worked.
3. Marking the paper as you go along- This saves time and gives you an incentive. Once you get a question write, it gives you more of a drive to carry on. It also makes the whole thing a little bit less monotonous.
4. Revise the que cards and then do the same paper again- I know it sounds stupid but you should theoretically get 100% after revising the que cards. This eliminates your strong points and lets you focus on your new weaknesses.
5. Try and gain audio explanations- I find this is key if you have taken a science but it can also be helpful in subjects like English too. This was you do not feel guilty about leaving your work and the concept drills into your head, just as the words to a song do.
6. Listen to music- Not rock, dance or anything heavy but maybe acoustic songs, Spanish guitar or classical music. This stops you from getting lost in your own thoughts and makes you concentrate on the task at hand.
7. Cram- This one is a bit controversial but personally if my exam is later int he afternoon, I'll go to the library to go over the key bits one more time and anything I've forgotten to cover. It may only store in your short-term memory but at least it's there!
My advice may not work for everyone, so I am really sorry if this does not help. These tips would probably be more useful if you are kinesthetic/visual learner.