Well A) use a better and thinner font, b) when you turn the curved text to a selection, choose the feather border option (set to 1 pixel) to make the edges of the text non-pixelated, c) increase the letter seperation on some of those.
Also it looks like you stroked some of those text paths (the palestine and greece ones) rather than got a selection from them.
Also you may not have set your Image->Mode to RBG rather than Indexed, that enables better alterations and generally smoother curves (Indexed is for when you want smaller file sizes and less system resources used)
See here is unfeathered and 'feathered' seperated text selections (effectively aliased and anti-aliased), with the second feather one set to reduced opacity to make it look more awesome.
Edit: On closer inspection your png image settings are set to indexed - thus stopping you from having soft edges, change it to RGB.
Also it looks like you stroked some of those text paths (the palestine and greece ones) rather than got a selection from them.
Also you may not have set your Image->Mode to RBG rather than Indexed, that enables better alterations and generally smoother curves (Indexed is for when you want smaller file sizes and less system resources used)
See here is unfeathered and 'feathered' seperated text selections (effectively aliased and anti-aliased), with the second feather one set to reduced opacity to make it look more awesome.
Edit: On closer inspection your png image settings are set to indexed - thus stopping you from having soft edges, change it to RGB.