Theory:

What is self pollination?
The transfer of pollen grains from the anther to the stigma of the same flower or another flower on the same plant is known as self-pollination.
Self_polination.jpg
Self pollination
  
It is also known as autogamy and is seen in bisexual flowers (that contain both stamens and pistil) like Hibiscus.
 
Advantages of self pollination:
  • In bisexual flowers, self-pollination is possible.
  • It does not depend on the agents for pollination.
  • Pollen grains are not wasted.
Disadvantages of self-pollination:
  • Less number of seeds are produced.
  • Due to limited amount of endosperm, seeds produce weak plants.
  • New varieties of plants cannot be produced.
Cross pollination:
The transfer of pollen grains from the anthers of a flower to the stigma of a flower on another plant of the same species is known as cross pollination.
1024px-Cross_pollination.png
Cross pollination
  
Advantages of cross pollination:
  • Cross-pollination results in the formation of new varieties because the seeds produced by cross-pollination develop and germinate properly and grow into better plants.
  • Comparatively, more viable seeds are produced.
Disadvantages of cross-pollination:
  • There are high chances for pollination failure due to the distance barrier.
  • Pollen grains are wasted in high amounts.
  • Cross-pollination may result in the generation of unwanted characters.
  • It depends on external factors for pollination.
Reference:
https://upload.wikimedia.org/wikipedia/commons/1/14/Self_polination.jpg
https://upload.wikimedia.org/wikipedia/commons/thumb/c/ce/Cross_pollination.png/1024px-Cross_pollination.png