SharePoint 2010: solution/feature upgrade recommended practices -

This is an open question: I try to define a set of recommended exercises to give a SharePoint to a team Solution in Phase I mean, the change will be at every level (solution, convenience, web part, content type, etc.)

On your experience, in fact, in fact, have you worked for people? Using Upgradation Custom Actions for Previous, Does the FeatureUpriding Event Handle Contain a Fully Renewal Logic? Or can the feature feature already exist in the featureactive handler? other?

I am asking because I know about projects which adhere to the words from many MSDN articles on it and still, it is very frightening to upgrade management, Ever average gods

Thank you! My current view is:

As no one answers,

1. Use the declarative approach for those cases where it works 100% of the time

3. <

5. Against the former or post-upgrade state