This is a recent topic of conversation in some of the areas of the web that I go to on a daily basis. What does this mean? How does one go about it? What do you do? How fast do you change yourself?
I know many questions right?  When I think of going plain, I think of Mennonite/Amish lifestyle.  I think of no electricity, no computer, and no phones. I think of canning and I think of raising your own beef. Ah the simple times. Is it?  I also think of the Amish Kapp and the dresses.  I think of the veil some of the sisters wear and maybe jumpers. Simple home made items. Is it really all that simple?
Going plain should be more of simplicity then what the Amish do. Simplicity to me is washing machines and telephones. Electric lights and electric sewing machines. Simple. Keep it simple. If you love to can, then can.  If you want to raise your own beef then do so. Don't do it to gain "simplicity" You are just not going to find it.  I think God sums it up well here:

Phi 4:11  Not that I speak in respect of want: for I have learned, in whatsoever state I am, therewith to be content.

Be content with what you have. Not what you do not have.
If you are going "plain" to be more modest. Let’s look at the Amish dress. Yes the cape part is modest double or even triple layer but what about the skirt. Where does it end? Most I see end up just below the knee. That is not MY idea of modesty. Why bother with the cape part at all? Some are longer and that's a good thing. This is just all of my own humble opinion.
Coverings: Are you going "plain" to wear a covering? You can cover without being "plain" It is a modest thing and I dare say, women ought to cover. It was just till the 1900's the ladies stopped wearing a hat or covering to church. What changed? Woman liberalism changed it. Sad.
With this all said, I think I am more "Plain" then some. I wear long modest jumpers and dresses. I wear a head covering. I am starting to cook from scratch. I am not doing this because "I" want to; I am doing this because God has told me to. He has laid it on my heart to follow his plan. I am to dress like a lady, I am to cover my head, and I am to care for my family. We are told to do all of this. I do it because the Lord has said so; I am going this way because I want to find contentment. I want to be content. I want happiness. Going "plain" isn't going to give me these things, but, God will. When I stop trying to be like the world and be in the fast lane all the time, I will find these things. Am I going to raise my own beef? No. Am I going to can? Maybe. Am I going to go without lights? Only if I have to. Will I have an electric sewing machine? You better believe it. Simple is what I am looking for. I love simple.

Phi 4:11 Not that I speak in respect of want: for I have learned, in whatsoever state I am, therewith to be content.

I forgot to add in, Plain is Anabaptist such as Mennonite, Amish, and Charity.

plain is homesteading, cooking from scratch and things like that.