I saw the word "discipline" used in the context of children and I really thought I should refer you to two authors.
First, please see Alice Miller. Her website is www.alice-miller.com. If it's down, you can access it using the WayBackMachine at www.archive.org. Please do read her books and/or her articles. Many of us treat children in very damaging ways, causing them psychological harm when they become adults.
Second, please take a look at Alfie Kohn (www.alfiekohn.org). His latest book, "The Myth of the Spoiled Child," should be of interest.
I really appreciate your effort to be a better parent than your own parents. I would give you detailed comments but I think Alice Miller's and Alfie Kohn's material are best approached on a first-hand basis.
P.S.: I wanted to leave this as a comment but I do not have enough reputation to do that. I dislike this system of needing reputation to do something as basic as commenting on someone's post.
After reading the comments to my answer, I thought I'll add more details. Some disclaimers: First, I am not a parent. But I was a child once, and I know many who were children once, and I draw my knowledge based on my own experience, and on the experience of countless others. Second, I do not mean anyone any disrespect; I understand parenting must be tough, and to do it right when a lot of us (usually) have had crappy parents, that must be really difficult. Maybe I'll know that feeling someday myself.
I agree with A.S. Neill (author of Summerhill: A Radical Approach to Child Rearing and Freedom, Not License!) when he says that children have natural phases and that we have to let them live out their natural phases instead of trying to control them, and instead of trying to suppress their vitality.
You say that they make a mess while eating. Why not let them make a mess? They do not have the same notion of "neatness" as us, so it is clear that they will make a mess. Why do you think them making a mess is a bad idea? Is it because you have to clean them up and you really do not want to because your wife and yourself had work all day? Or is it because you think they might not know how to have proper eating manners when they grow up?
I quote from A.S. Neill's Summerhill here:
The common assumption that good habits that have not been forced into us during early childhood can never develop in us later on in life is an assumption we have been brought up on and which we unquestioningly accept merely because the idea has never been challenged. I deny this premise.
A. S. Neill talks a lot about giving chilren love and freedom, and not to be manipulative of them. He says that if we let children live out their natural phases, they will get to a point where they understand, through their own opinion, about why being neat matters, for example. Do read the two books I cited, Summerhill and Freedom, Not License! to see Neill's decades of experience running the Summerhill school (http://www.summerhillschool.co.uk/).
I think that in many cases, we adults suppress the vitality and the reactive feelings of children, who in many cases, are unable to express their true emotion and resort to tendencies such as spitting and screaming and hitting each other. I think that our tendency to resort to "discipline," is misguided, because not only are we being extremely manipulative to our children, and not only are we suppressing their vitality and their natural needs, we are also failing to recognize their true needs. We are also failing to give them unconditional love, and they desperately need our love! Many times, we impose this discipline for our own selfish needs (maybe because we need the peace and quiet, or maybe we do not want to clean up their mess).
I asked you to read Alfie Kohn, and Alice Miller, (and now A. S. Neill) because in their writing, they make us question the underlying assumptions and norms in society, and they make us reflect a lot on our own childhood (Alice Miller does this very well).
In addition to Kohn's book The Myth of the Spoiled Child, I would also recommend looking at Unconditional Parenting (http://www.alfiekohn.org/up/). I have not read either of them yet (they are on my to-read list) but I recommend them on the basis of being familiar with Kohn's other work, and of being familiar with Kohn's general line of thought. Here's a quote from the Unconditional Parenting book website (bold emphasis mine).
One basic need all children have, Kohn argues, is to be loved unconditionally, to know that they will be accepted even if they screw up or fall short. Yet conventional approaches to parenting such as punishments (including "time-outs"), rewards (including positive reinforcement), and other forms of control teach children that they are loved only when they please us or impress us. Kohn cites a body of powerful, and largely unknown, research detailing the damage caused by leading children to believe they must earn our approval. That's precisely the message children derive from common discipline techniques, even though it's not the message most parents intend to send.
More than just another book about discipline, though, Unconditional Parenting addresses the ways parents think about, feel about, and act with their children. It invites them to question their most basic assumptions about raising kids while offering a wealth of practical strategies for shifting from "doing to" to "working with" parenting - including how to replace praise with the unconditional support that children need to grow into healthy, caring, responsible people. This is an eye-opening, paradigm-shattering book that will reconnect readers to their own best instincts and inspire them to become better parents.
I have read much of Miller's work. I started out by reading The Truth Will Set You Free (http://www.alice-miller.com/books_en.php?page=10) and The Body Never Lies (http://www.alice-miller.com/books_en.php?page=11). You might like those two. Many others start Miller by reading her first work The Drama of the Gifted Child.
I hope this helps. I am aware that my response appears to be of the type "read these books and you'll be fine." But my intention really is to point you in the direction where we question the accepted norms of child-rearing, such as "discipline," so that we may collectively give our kids a far far better childhood, a childhood that all children deserve, a childhood that many of us were denied.