Most common PM Methodology is Waterfall, however Spiral and/or Agile are rapidly taking over as leading methods.  See video for thoughts on this...

Often people think these more iterative methodologies are for software projects, but one can easily follow the approach across all industries.  It is a way of thinking, follow that "Deming" model (plan, do, check, act and repeat).

One way you can think about this spiral approach is to maintain the waterfall methodology at the highest level (for strategic planning and the executives) but at the WBS level you need to manage your project following a more modular approach.  Break apart your projects into mini projects and have as much independence as you can.  So the effort required for "Integration" will be much higher.  This is similar to an approach followed when managing Programs (so you could also look at it from that perspective).

Embrace the change and the ability to be flexible and adaptable while rolling out your project.  Have a very good, rapid change control process.  This does not mean do less planning, it is the opposite, you will have to have more planning but it is just with a more dynamic approach.