You should download this table and print it out to help you with your dermatoscopic diagnosis.
Mind you , you can reduce dermatoscopy to the following
1 One pattern, One colour = Benign leave
2. One pattern and More than One colour + Clue to Melanoma then excise
3. One colour and more than one pattern + Clue to Melanoma then excise
4. More than one colour and more than one pattern then consider excising and any Clue to Melanoma will clinch that decision.
Dermoscopy structures Table
You might also be interested in this excellent short summary of Harald Kittler's algorithm by Dr Jean- Yves Gourhant