If you want to dual wield I don't really have any experience but for greatswords/ultra-greatswords and just 2-handing them I would get about 20 strength and ~10-15 dex to use the early strength weapons. Remember that you can two-hand strength weapons as long as you have half of the required strength. Using two weapons requires 1.5 the str and dex requirements of the given weapons.
Starting out, depending on which class you pick, I would get endurance up to at least 10 before putting points into anything so you can attack a couple times and then be able to dodge out of the way to fill your stamina tank up again. After you get a minimum amount for whatever weapon you're going to be using at the beginning I would raise ADP until your agility is about 95ish, then go back to END and VIG for health and stamina; a bit of VIT if you want to wear heavier equipment and roll further.
I personally prefer 100-105 agility because I don't have a shield to rely on. The minimum stat requirement for a weapon is alright to start with, especially with ulta-greatswords you're going to be 1-2 shotting most normal enemies anyway.
This is where I'm at right now rebuilding my first character:
I plan on eventually getting 30 str, then either 20 dex or going to 40 at least with VIG and END. The most important part for damage output early on though is just upgrading your weapon of choice.