Funny you brought this up. I have never read any Dick. Been meaning to for 20 years.You've inspired me to correct that egregious oversight by reading Ubik as soon as possible.
So I'm no help to you with your question, but for what's it's worth, since you said you are new to science fiction, you might start with Spares and One of Us andOnly Forward by Michael Marshall Smith, who wrote the intro in your Ubik edition. All 3 are terrific.
Other personal favorites:
Hyperion and Fall of Hyperion - Dan Simmons
Ender's Game and Speaker for the Dead- Orson Scott Card
Spin - Robert Charles Wilson
The Handmaid's Tale and Oryx & Crake - Margaret Atwood
Contact - Carl Sagan
The Risen Empire/Killing of Worlds - Scott Westerfeld