I have taken a few classes on Barth and read a good amount of the Church Dogmatics. Its been awhile since I read any Barth, so I don't remember all the tools I had in my toolbox. My biggest advice would be to read through a chapter without reading the excursus (the part in small font). Barth goes into a lot of tangents down there which are full of really helpful pieces, but take you away from the main argument. Read through the big font first, then go back and read the excursus.
The other piece of advice is don't be afraid to read the main source alongside any number of helpful outlines and overviews. Dogmatics in Outline is one that Barth wrote himself. I really found Otto Weber's Intro to the Dogmatics to be very helpful. There are a bunch of outlines to check out.
If you are feeling really overwhelmed, it might be helpful to read Evangelic Theology. Its a relatively easy read and it will help you get oriented to Barth's style and theology.
There is a summary of Dogmatics out there which is quote good (an outline written by Barth himself): "Dogmatics in Outline". http://www.amazon.com/Dogmatics-Outline-Karl-Barth/dp/006130056X
Two more useful, and manageable, works of his include:
Credo: http://www.amazon.co.uk/Credo-Karl-Barth/dp/1597521191
The Humanity of God: http://www.amazon.co.uk/Humanity-God-BARTH/dp/0804206120/ref=sr_1_1?s=books&ie=UTF8&qid=1429357431&sr=1-1&keywords=humanity+of+god+barth
I'd also direct you to a wonderful Christian theological textbook, "Faith Seeking Understanding", which spends a fair bit of time thinking about Barth as well as a number of other perspectives. http://www.amazon.co.uk/Faith-Seeking-Understanding-Introduction-Christian-ebook/dp/B0026IUOZA/ref=sr_1_2?s=books&ie=UTF8&qid=1429357545&sr=1-2&keywords=faith+seeking+understanding
My personal favourite is Pannenberg, but I'm not going to lie to you: It's a dense read, and demands of its reader a fair bit of familiarity with other theologians. That being said, if you can make your way through it, it is very rewarding.
Millard Erickson does a pretty good job of a rigorous theological overview of Reformed evangelicalism.
Grudem is absolute garbage, avoid like the plague.
Stanley Grenz is a pretty good candidate. Like Erickson, he writes from a sort of Reformed evangelical perspective, but he's got much more of an eye for ecumenicism, and tends to have more emphasis on interacting with other traditions. He's actually a big advocate for Pannenberg, and in my reckoning one of the main reasons why Pannenberg has been gaining steam in the Anglo world recently.
I suspect the people who suggest Barth's Church Dogmatics are joking, as reading and understanding the Dogmatics is quite literally a lifelong project. If you feel up to the challenge, then by all means, go ahead. Otherwise, Dogmatics in Outline might be a better option.
So, in summary, I might recommend either Erickson or Grenz, and then once those have whet your appetite, maybe moving on to Barth or Pannenberg