I recomend you fight Emerald first I always found him to be easier, I can't be bothered to write a huge long stratagy or anything but I'll tell you the materia you need the most; Knights of the round paired with w-summon, Pheonix paired with final attack, mime materia on at least two characters paired with MP Absorb or Turbo (can't remeber which) and a enemy skill with angle wishper just incase
Tip, easy ways to lvl up materia:
collect the w-item materia from the tunnles during your last visit to Midgar and use the w-item trick to get 99 Elixers (well...quite a few anyway) then go down the Northen cave and give the magic pots Elixers.
also down the northern cave are Movers, they give you loads of AP for finishing them off.
Hope this helps...