Find a pal of similar level and it's much easier.
ONE pal, not two.

Solo tactics is usually for high end players where difficult makes teaming up kind of moot (due to damage scaling and poison unable to be removed and stack), hard to find a partner (should you be one of the highest level, as having level difference is bad as lower level contribute very little) and finally, go for the ranking (only solo ranks).
If you are having trouble with easy, the easiest solution is always find ONE friend to two man it, as easy difficulty or even medium is very easy with 2-man team. If nothing, the fact that between two nejis you can acupuncture to stop the poison EVERY turn make it a walk in the park. (that and the combo required per person is reduced)