Reddit user Wafflyn made useful Blueprint and C++ cheatsheets for anyone using UE4. From the post:

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Made these cheat sheets for myself and others as I remember first starting out with UE4 transitioning to UE4 style of C++ there were many unknowns. Mostly focused on beginner's needs currently for these cheat sheets.

UE4 Blueprint Cheat Sheet: http://uecasts.com/resources/unreal-engine-blueprint-cheat-sheet

UE4 C++ Cheat Sheet: http://uecasts.com/resources/unreal-engine-c-plus-plus-cheat-sheet