I've been playing a lot of Diablo 3 while I wait for Reaper of Souls to come out. Here is a list of what I'm doing (and what you should too).
1. Making Real Money on the RMAH
Come on, this was a given. The auction house is going away and right now gold is super expensive! The price is almost $3 per 50 million and so I'm hustling on both auction houses to turn a profit. What I've seen so far is that the low level stuff for leveling is doing phenominally well. Also the level 60 high stat rares for gloves, shoulders, rings and amulets. We're talking just straight up vitality, primary stat, and any damage affixes possible for the item (crit chance and damage for rings/amulets/gloves). People are gearing out their characters quickly for the expansion and paying good amounts of gold/money to do so.
Use my guide and apply it to mid level items as well as max level rares. The legendary blueprint is still king on the guide, despite its age.
2. Get Your Hell Fire Rings.
Do the current end game content over and over again until you have tons of hell fire rings. You especially want a strength one for the Crusader hero that's coming with the Reaper of Souls expansion.
3. Hit Paragon Level 100
If you get well geared and equip a hell fire ring, you should be able to do monster power 5-7 quickly and efficiently to level up to 100 paragon. For each character you max out, Blizzard is going to reward you with additional paragon levels in the expansion. The conversion is small, in favor of the new paragon levels, but worth doing while you farm for items.
I've decided that no matter what I will update the guide to include farming strategies. Depending on what happens, I will make the forum open to everyone for free. So please, just buy the guide and don't buy any more forum time.