renderin (the more easy), Light Up... 😉

the more fun Lumion free animation and fixed image (maxi 1920*1080)

first, learn the basics by doing simple stuff. just give yourself a task and try to do it. SU is really intuitive. when u hit a brick wall, use the search function on this forum.- also read this thrad http://forums.sketchucation.com/viewtopic.php?f=79&t=12706 and this one http://forums.sketchucation.com/viewtopic.php?f=15&t=17315&p=360018 over and over 😄

here is a thread with .gifs of some good plugins http://forums.sketchucation.com/viewtopic.php?f=323&t=16909&hilit=plugins - but dont use too many plugins before u have the basics down.
here are all plugins in one thread: http://forums.sketchucation.com/viewtopic.php?p=250026

for archviz i mostly use Fredos Round Corner, Joint Push Pull, Selection Toys, CleanUp³. I have many more plugins but rarely need them. but it really depends what u are doing with SU.

terrain generation: sandbox tools

for a rendering beginner, i would recommend free maxwell. u basically just press a button and get a photorealistic rendering.