Recommended · for some experience
Electronic Basics #3: Programming an Attiny+Homemade Arduino Shield
Why people recommend it
GreatScott turns an Arduino into a programmer for the ATtiny85, the usual pointer when someone wants to shrink a project onto a smaller chip.
Watch for: Upload errors can crop up when following along
In their words
Recently I ordered some ATtiny85's from Jameco, and I've been trying to upload code to them through an Arduino Uno, following the instructions from this video on YouTube.
Gᴇᴏᴍᴇᴛᴇʀ on arduino.stackexchange.com, Feb 2016. CC BY-SA.