Heuristics for Building a Diablo IV Character

Diablo IV's next season is coming up, so I thought I'd lay out some heuristics and strategies for getting a semi-decent build. Now, none of these will compare to a true pre-made build from the various websites, but I think they're a good skeleton for a player to experiment with.

1. Diablo IV is built around builder-spender gameplay. Generally only take 1 builder and 1 spender.
2. One of your abilities (usually the spender) will be your main source of damage. Only put multiple ranks into this ability. Just take 1 rank of the other abilities you want to use. Other than your main ability, focus on passives.
3. The legendary aspects you put on your gear are your "set". The priority for the early game is figuring what your "set" looks like and assembling the necessary aspects. After that, just keep imprinting your set on new gear.
4. Put your best aspect on a 2H weapon (2x effective) if you are using one, otherwise on your amulet (1.5x effect). 
5. While levelling, temper your gear with the basic stats. The more exotic stats generally need a full build to take advantage of.
6. As for gear, just upgrade whenever you can. You can worry about specific stats once you hit Ancestral gear.
7. Unique items are powerful, but don't use too many. Much of your power comes from your "set" of legendary aspects, and each unique you use causes you to lose one of your set pieces.
8. What sort of abilities and special effects you focus on depend mostly on your build (i.e. crowd control, burning, overpower, etc.). But you need an easy, regular source of Vulnerable, be it ability, aspect, paragon glyph, etc. You should have it by the time you hit Tier IV.
9. For the paragon board, your first priority is glyph sockets, and enough ability points to activate the secondary power of the glyph. Then paragon nodes if they are good for your build. You should aim for at least 5 sockets. Pick up rare and magic nodes if they are close by, but focus on the path between sockets and paragon nodes.
10. Personally, I think D4 works best when you do a wide variety of content. Mix things up.

Obviously, these tips will only take you so far. The meta-builds on the various websites will most likely be stronger. But these heuristics will give you some direction if you want to try a home-brew on your own.