Recently, I built a simple validation framework which can work with WPF. I found I can use class attribute and reflection to achieve this purpose.
Firstly, I define a Required Attribute to see whether the property requires a value

Code

Then I add IsValid method in the class, it will use the reflect to get all properties in this class. Then it will check whether the property has "required=true", if that is the case, it will check whether the property has value, if not, it will use an error.

public class PersonModel
	{
		[Required(true)]
		public string Name {get;set;}
		public IList IsValid()
		{
			IList ret = new List();
			foreach (var prop in this.GetType().GetProperties())
			{
				foreach(Attribute attr1 in  prop.GetCustomAttributes(typeof(RequiredAttribute),true)){
					RequiredAttribute attr = (RequiredAttribute) attr1;
					if (attr != null) {
						if (attr.Required)
						{
							if (string.IsNullOrEmpty(Convert.ToString(prop.GetValue(this, null)))) {
								ret.Add(string.Format("{0} is required",prop.Name));
							}
							
						}
					}
				}

			}
			return ret;
		}
	}

is the best practice. I cannot think another way can do it easier.
Please click here to download the example code.