Hi!

I do portrait photography and have the doubt on how to get BLUE skies and correct expure on my subjects without using flash.. I always end up having these results:

http://i611.photobucket.com/albums/tt194/javrilaphoto/2011_07-16%20Cindy%20and%20Steve%20engagement/CindySteve_148.jpg

http://i611.photobucket.com/albums/tt194/javrilaphoto/2011_06_17_Emily/Emily-139_JCphotografiacopyright2011blog.jpg

Any help will be much appreciated

They make reflective surfaces to bathe your subject in a glow instead of a flash. Another way to prevent wash outs is to take your meter readings at your subjects. Also if you are using an slr you can use a filter (its actually called a sky filter or UV filter) to obtain that rich blue sky while maintaining the whites and greys for clouds.

Also when shooting bracket your picture taking and make notes. From there you will gain experience as to what works best.

Agreed, bracket your shots and try different apertures...

Your shots look like you may be over exposing with a combination of large aperture and slowish shutter speed... If your camera has an aperture or shutter priority mode give it a try...
If you want the blurred background, set to Aperture priority and let the camera set the shutter...

Adjust your white balance settings to get better results and keep your ISO as low as possible (50-200 range for outdoors in daylight... )

There are different types of reflectors that you can buy. (They look like car windshield shades... ) Some are white, silver, and gold... They sell them individually or as combo packs (white on one side, silver on the other, maybe a separate gold in the pack... ) They aren't cheap, so until you have enough cash to buy one you can always reflect white light with a large sheet of paper or a project board...

Alternatively, you can still use a flash without over exposing and washing out detail by bouncing the flash off something (a wall or a reflector like what I mentioned above, the paper and project boards too... ) Bouncing takes practice, but you can get nice results if you have the patience...

I hope this helps...