Important/really good episodes?

Here are some episodes from seasons 1 and 2 that i would recommend.
Season 1:
Pilot-Extreme Aggressor
This gives you an introduction and a bit of background info on the main characters.

Ep 3-Wont Get Fooled Again
Ep 9-Derailed- a psychological episode with a really good performance by Dr Reid.
Ep 14- Ride The Lightning- Its intense and sad
Ep 17- A Real Rain-Good episode about vigilantism.
If you want to know a bit more about Dr Reid watch The Fisher King Parts 1&2 which is the last episode in the 1st season and first ep in season 2. I dont like it, but you might!

Season 2:
Ep 4- Psychodrama
Ep 5- The aftermath- sets up a character departure
Ep 10-Lessons Learned- Introduces Prentiss and is an excellent episode all round.
Ep 11- Sex Birth Death
Ep 12- Profiler Profiled- I dont like this episode but you learn alot about Morgan.
Ep 13-20- Alot of Character development featured and storylines that are in the most recent season eps, begin in these episodes.eg Reids drug addiction.

I hope this helps. Let me know if you want me to recommend episodes from Season 3. Otherwise Enjoy!!!