Web Controls and Accessibility (which is right?)

I wish there was a clear list of Do's and Don'ts for web contols. It would be nice to simply look down the list of each control and make sure you have everything you need. I see so many alternative stuff online and not enough detail in each case.
Which is correct or does it matter?
<asp:LinkButton ID="lbtnCancel" runat="server" OnClick="lbtnCancel_Click" Visible="false" Text="Cancel"></asp:LinkButton>
<asp:LinkButton ID="lbtnCancel" runat="server" OnClick="lbtnCancel_Click" Visible="false" >Cancel</asp:LinkButton>


<asp:Label ID="lblInfoSecurity" runat="server" AssociatedControlID="ddlInfoSecurity" Text="Info Security:"></asp:Label>
<asp:Label ID="lblInfoSecurity" runat="serv ...