Most of the game content nowadays is pretty much duoable, with the exception of the newer endgame activities. If you want to get good gear and fast, I suggest you and your friend level some good jobs combo for abyssea farming. AKA:
Seals = blu/nin (or nin/dnc for tougher NMs) + blm/rdm (or whm/blm for tougher NMs)
Key Items= war/nin + whm/rdm
Monster Drops= mnk/war + whm/rdm (or thf/dnc, if the NM doesn't require a healer. having all blunt procs + treasure hunter is a good idea)

The 'perfect' set ups for abyssea usually require 3 people but as you can see, even with just two you can get a good chunk of most of the procs. Of course, this means you also need to skill up a lot. It takes time, but all the good stuff in this game does. I'm on Siren and wish you the best of luck. Wish I was as lucky as to have a pal to duo with like you do! Solo has became a curse of no game progress unfortunately, and by solo of course I mean 'one character'. Dual/Triboxing doesn't count.