I got 6s all year for both English Lang and Lit. Be confident in your writing, and make sure basics are correct in terms of grammar, spelling and structure. What I found helped with the books (mostly Macbeth, as that killed me), was mindmaps - do part on context, part on characters, part on key themes and include quotes in these areas. Also extend your vocabulary, so that you seem far more into the subject than you probably really are...
For Geography, I'd say make posters. Posters are good for the main parts (so hazards, do a poster for each hazard for example). I think the main part of Geography is case studies though, as if you remember the case studies you'll remember the theory behind it (mostly for human stuff, for physical make sure you remember the key words and phrases). For each case study, outline it in as much detail in a word document and compile them all together for each topic. Then, create flash cards as a summary for each of these, and make sure to remember some facts, figures and dates for these as they're the true indicator that you've learned them.
Sceince - state the obvious. Build it up. Make sure you understand the basics of what you've been learning. Back in the day when there were six markers, you'd have to make sure you'd know the basics and then elaborate. Best thing for this is flashcards - make flashcards on literally everything! That's how I got my As in sciences.
Maths is formulas and practice.
Good luck!!