1) Avoid abbreviations myPosition not myPos (follows Qt convention)
2) Class members get prefixed by 'm' e.g. QgsPoint mLastPosition
3) Class members that are pointers get prefixed by 'mp' e.g. QgsPoint * mpLastPosition
4) Member paramters get prefixed by 'the' e.g. void foo(int theValue);
5) Member paramters that are pointers get prefixed by 'thep' e.g. void foo(int * thepValue);
6) Variables with local scope get prefixed with 'my' e.g. QgsPoint myPosition;
7) Variables with local scope that are pointers get prefixed with 'myp' e.g. QgsPoint * mypPosition;
8) Widgets drawn with designer get no prefix and use the following prefixes
   (this is one case where we break the no abbreviations rule)
   
   QLineEdit  - 'le' e.g. leName
   QTextEdit  - 'te' e.g. teName
   QTextBrowser - 'tb' e.g. tbName
   QSpinBox - 'spin'
   QDoubleSpinBox - 'spin' (carries same semantics as above)
   QLabel - 'lbl'
   QGroupBox - 'grp'
   QSplitter - 'splitter'
   QTreeWidget - 'tree'
   QTreeView,QTableView,QListView - 'tree' *1
   QComboBox - 'cbo'
   QCheckBox - 'cbx'
   QRadioButton - 'rad'
   QPushButton - pbn

*1 In general views are interchangeable, so using the same prefix for all 
  allows easily swapping e.g. a list view for a table view in designer
  without having to change any code.

10) Using the above scheme, its very easy to identify the scope of any variable
    for example:

      void foo(
               QString theName,            <-- method parameter 'the'
               QgsPoint * thepPoint        <-- method parameter as pointer 'thep'
               )     
      {
        QString myShortName =              <-- Local variable 'my'
                     theName.subString(0,5);  
        QgsPoint * mypPoint =              <-- Local variable as pointer 'myp'
                     roundPoint(thepPoint);
        drawLabel(
                  thepPoint,               <-- Method parameter 'thep'
                  mColor,                  <-- Member variable 'm'
                  myShortName              <-- Local variable 'my'
                  );
        leName->setText(                   <-- Designer variable from ui baseclass 'le'
                  myShortName
                  );

      }