pagination vs. seo

how should pagination be optimized for seo? the default pagination for a blog is to start at 2 and then count up:

myblog/
myblog/2
myblog/3
myblog/4
myblog/5

but publishing a new post moves all the existing posts down one step. therefore paginated urls will have their contents completely changed after a few days.

google is obviously taking the challenge and re-indexing/updating these urls regularly. but can a location that has completely different content on every crawling attempt be trusted?

what's the seo solution for this? follow,noindex on paginated pages?
or create perma-paginating by month instead of counting?

The same goes with tag and category pages I think. they fall info duplicate content issues as well.

What is do is to noindex on page/tag pages and only index home/categories and individual posts.

But this is just me...