A question of nuances and degrees, I guess

[gnomygnomy.livejournal.com]

My book lists these verbs just like this:

бояться - to fear, be afraid of
пугаться/испугаться - to be afraid of
-------
избегать/избежать - to avoid
опасаться - to fear, shun, keep off, avoid
-------
держаться - to keep to, hold on to, adhere to
придерживаться - to adhere to, stick to


In each pair, I'm having trouble deciding when to use which verb. Especially for the first two verbs, of which the English definitions are... strikingly similar? In what contexts would I choose one over the other? Or are they practically synonyms, and can be used interchangeably?

Thanks, guys. :)