Sooooo many to list but I use youtube for the majority of my sources as visual instruction / walk-through is the best way I learn. Trial and error is a close second 
anyhow my list below:
https://www.youtube.com/channel/UCBobmJyzsJ6Ll7UbfhI4iwQ Unreal Engine
https://www.youtube.com/channel/UCOVfF7PfLbRdVEm0hONTrNQ Mathew Wadstein
https://www.youtube.com/channel/UCz-eYJAUgSE-mqzKtit7m9g Virtus Learning Hub
https://www.youtube.com/channel/UCiIl8Gex0kzhU48icQu_v_w The Sarg Kyle
Warren Marshall - YouTube Warren Marshall
https://www.youtube.com/channel/UCkIkWiM9gbAPe8MSrAahuqw 3 Prong Gaming
https://www.youtube.com/user/allright2910/videos Alexander Shatalov
https://www.youtube.com/channel/UCYP-Vz2YA-D7ZZIbEpBk0WQ Azem
https://www.youtube.com/channel/UCKJXFBJBppE7qiI7npzJPgw Ben Ormstad
https://www.youtube.com/channel/UCzGCEnrXAmh7h4VwcU8sXKg/videos Matt Taylor
https://www.youtube.com/channel/UCgqb66tX-DYAbAU93UcvTTA Devin Sherry
https://www.youtube.com/channel/UCCyYS9kMLEdB03GxJXqtmFQ/videos Evil Eye Games
https://www.youtube.com/user/evilmrfrank/videos evilmrfrank
https://www.youtube.com/channel/UCfyvlGW2gDNh5YH6CFh7BtQ JackX570
Joe Hudson - YouTube Joe Hudson
https://www.youtube.com/channel/UCgmX4icpN3HnOOwYtmyYz2w Maverick
https://www.youtube.com/channel/UCC8f6SxKJElVvaRb7nF4Axg PyroDev
RATSGAME - YouTube RATSGAME
https://www.youtube.com/channel/UCTA7ggbDBcF30GeSDysBoGg/videos SG Creation
Tesla Dev - YouTube Tesla Dev
https://www.youtube.com/channel/UCX44PoFn-gUJ2_8VYAaVrbw UnrealTek
https://www.youtube.com/channel/UCHuzwCBMsExSsORBmDzhGYA WorldofLevelDesign
https://www.youtube.com/channel/UCWfkqFjkMqQp6i-HwpWJ09A Yoeri-Luos-Vleer
UE4U - YouTube UE4U
https://www.youtube.com/channel/UCnO-xQvmsO1WwKFq-5Pvj0Q Tom Looman
https://www.youtube.com/channel/UCeQ19HRB5QT3Rwn7hCpugBg/videos Kyle D.
https://www.youtube.com/user/PeterLNewton/videos Peter L. Newton