Here are my examples-
Eevee/Absol-

Shiny Ninetales Recolor-

Umbreon/Houndoom-

Kairona(Dragonair form)-

Espeon/Mawlie-

Demonic Absol-

Hmm, not too bad. First of all, try not to save your sprites as JPGs; it ruins the quality. Secondly, pay special attention to the outlines. They shouldn't be all one color; they should have highlights and shadows just like the body of the sprite. The Umbreon/Houndoom has some all black outlines on the gray bone things; try making them lighter in places so it looks more realistic.

How about trying a Larvitar/Treecko splice?

These are cool. Splices are personally my favorite sprites, so... Do you think you could do a Pikachu and Sneasel splice?