Starting items: Warriors Tabi (1), Soul Eater (3), Meditation (1), Healing Potion (1).
Soul Eater gives 15% lifesteal and 300 health which is amazing for the sustain. One game I played with Neith I was able to get to level 18 without dying just by farming minions with Soul Eater.
Then when you go back finish off Warriors Tabi. I think Qin's Blades is a great 3rd item because it gives 30 physical power which is pretty good, and 25% attack speed which is great. The passive is also really good especially if the enemy team has high health.
The next two items are The Executioner and Fatalis. These give great attack speed which is necessary for maximizing the DPS of a physical carry like Neith.
I then finish off the build with Deathbringer and Rage, and at this point in the game Neith's dps is completely insane.
The critical strike chance is 56%, and grows 5% for every basic attack that isn't a crit (Rage's Passive.) The attack speed above double, because almost every item in this build increases attack speed.
So essentially when the build is maxed out you're spamming ~400 damage crits with 15% lifesteal.
Thanks for reading, this is my first guide so please leave me comments on how to improve it :).