Good info, ill chime in on some stuff.
Find a language you like, for me, I wrote a keylogger in python for windows, and in Golang, I actually moved to making physical keylogger device using arduino, and esp8266 with wifi, this project is done code wise, I just need to go in blender, and 3d model a enclosure for it, but ive been putting it off for months.
Anyways, This is something you need to do coding wise.
Dont use timers, hook the .dll file.
>have program first start by checking for antivirus installed, google around on how to check for AV.
>if there is antivirus, modify the system registry to accept your program as safe
>make a throwaway gmail and have keylogger send a text file every few hours or use a cloud service, and read the API documents on uploading files through your program.
Ok so deploying your payload.
Theres a book called
>social engineering: the art of human hacking
I would recommend reading
There was a couple of examples I read about planting USB devices from that book.
Examples:
>put a usb flash drive in the bathroom of the building youre trying to infiltrate, on the floor or on the sink counter
>or break/lunch room
>parking lot near cars
Those will probably be the most successful, Now, You can bind your program into a zip file, and name it something someone would be curious
>The Fappening PT 3 doesnt sound too bad