That is my item build and skilling order, plus a bunch of random other tips. I agree with most of what Kragorn said as well. If you're playing against fed people, you're going to have problems, and I wouldn't judge yourself based on that.
I'm actually usually pretty offensive as Morgana. People are terribly afraid of all four of your skills, so use that to your advantage. If you can hit someone with a Dark Binding, then Tormented Soil a split second later, that can take out a huge amount of their HP. Remember to autoattack them during their bound time as well, even if it isn't much, it helps. If you're facing a melee hero, never get anywhere near them, because you don't have to. You can be offensive from far away. Lastly, always play with friends. With another champion, you are an amazing ganker and very survivable, but without one, you will die very quickly. If your lane partner is incompetent, you are going to have problems, and shouldn't blame yourself for that.
Edit: Updated the guide with some of the things I just said. Another thing is, check to see if the enemy champion has Mercury's Treads. You can't do anything to them if they do, so let your teammates deal with them.