I have done all the fundamental papers and I would suggest you to sit the it in the following order:
F6 (the rules change each June from what I remember, so definitely sit this in June/September, so even if you have to resit, you will not have to learn new rules again) F8 (this is a wordy paper so you could do it in any order you prefer) F9 (I found this the most difficult) F7 (closer to when you are planning to attempt SBR as F7 knowledge would be very beneficial, so maybe leave this til the end)