I recommend this
>>15122841 OP, unless you're a nostalgiafag who will never touch Pokemon again, after FireRed.
If you want to push forward through the gens, do it like this:
FireRed > EmeraldThis one is OPTIONAL, You may not like this one, jumping in after Red[/spoiler:lit] > HeartGold
It's a direct sequel to FireRed > Platinum > Black > Black2OPTIONAL sequel. I personally love it, but if you are still on board with the series at this point, you'll probably want to jump straight to the latest games after Black, which is completely ok > X
Have fun.