Will/Rough/Resist should be stats you want to focus on.
staying in the back away from enemies casting from range is idea.
As for companions its always up 2 the player i personally prefer melee companions since it lowers the chance enemies will go past them to get to me so im free to damage/heal at range without much issue in having to keep myself alive
Since witchdoctors specialize in staves and wands, those are the kind of weapons that you want to mainly use. Staves have a short range but big damage and can attack multiple enemies at once to make up for it, while wands have smaller damage and can only hit one enemy at a time compared to a staff but can hit from farther away (range is 5-6 depending on the wand) to make up for it.
In the later worlds of marleybone & Aquila, there are some melee weapons that use will for damage boosting, but until then, focus on using staves and wands as again, those are the main weapons of choice for witchdoctors, so there's that at least.
For companions, it depends on your personal preference, but I would personally recommend using companions with decent damage and survivability so you can last longer in a fight.
as a level 50 witchdoctor you should have more then enuff skills to never run into using normal attacks and risking missing(fizzle).
SKILLS never miss (fizzle)
I don't think I've used a regular attack as a WD since before level 20. As stated, skills never miss/fizzle, and Witch Doctors have so many skills, that in a typical battle, you won't even see (or right click away) even half of them. I was grateful when I was able to train mojo echo since I was finally able to see what my staffy/shooty attacks looked like!
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Always use your talents/powers. There are many new weapons that use both staffy weapons and any other type of weapon you wish to use. You also have to learn to use your powers effectively, use buffs correctly, train your companions properly.
There is so much in this game, best to do a bit of research, learn what to train in your practice points, learn what to epics and talents to give your companions, the best gear to use for your level. If you are only worried about health, then you are making yourself weak.