I regret that I didn't start with a FF camera. I didn't know what to get, so I tried to follow the most popular advice for beginners, which was/is like:
- body doesn't matter, half-dead Rebel is fine ; (not for me)
- get the best lenses you can afford ...; (best doesn't mean the most expensive)
- ... which are 11-16/2.8, 17-55/2.8, 70-200L, 100-400L; (not really, primes work better for me)
- don't forget about accessories: tripods, flashes, filters, etc; (you can buy these later, if you feel the need) (IMHO, only memory cards, bags and spare batteries are the must-have, everything else is optional).
Now I know that it does not fit my style. I don't need to cover the 16-600mm focal range. I rarely use tele lenses, flashes, tripods, filters ... no need to spend money on that. I should have bought a used 5D with 50/1.8'II and then add 85/1.8USM later (which I recommend for portraits).
The problem is that you never know before you try it. My current choice is 6D+40/2.8STM (people, close-ups, stitching landscapes, travel) +150/2.8Macro for portraits and stuff outdoors.
+1. Find your style first before buying all that extra stuff. You may find that you use a filter about once a year. Don't buy anything until you find a definite need for it. Try without it. You might find a cheap workaround. For example grad ND - I find lightrooms grad filter way more flexible or take two exposures and blend in photoshop. For ND filter - f/22 does the job (well kind of!). Maybe a CPL is one you will need as thats not possible to replicate digitally. Tripod - my knee, lampost, railing etc. even used someones shoulder once.
When you catagorically cannot go further - then buy it.
I can agree to almost anything except FLASH. I consider flash as one of the most important accessory besides lens and camera. You can use it as a fill-in flash which makes portraits a lot better. It's also a great help for extending a little bit a picture's DR. I can live without a tripod (most of the time) and filters but I consider flash as a must whenever I take pictures except for some situations. You may argue that 6D can take a much higher ISO but when you know how to use your flash properly, your pictures will be a lot better.