>>1063306 (OP)
Read through the security portion in the back of the book. Make sure your programs are locked down. Do an intermediate tutorial series in your given language on YouTube or something like that. Find ebooks or turtorials on network progamming, AI, game programming, or learn to create really cool GUIs. If you make Linux GUIs people will appreciate it.
Learn how to hack, then pentest your own applications. Write some hack tools. A hash cracking programming is an easy start and it has a legitimate purpose. Pure brute force with nested loops or a dictionary attack with read through a file line by line and try the hashing algorithm against each string and compare to string output the corresponding plaintext if the hashes match. Pretty simple.
Web authentication with curl.
Port scanners can be kinda fun. You can go really simple or you can put a lot of bells and whistles into it. Try to make a program that will find a specific service like image board sites, or check if site is given server is running http/https common ports 80 8080 8000 443 etc then parse the html for a given string like 'Tinyboard Copyright © 2010-2014 Tinyboard Development Group' or something like that.
Find a piece of software that is a pain in the ass to install and write a script for it.
Like if a C++ program has an #include statement that has the wrong library path write a program that will read through the includes and use a program like whereis to return the correct library path and check if the it's right in the source code and if not change it to the correct path before compiling.
Write an install script for various cryptocurrency wallets and miners.
Write an application that will turn your plaintext or rich text into HTML pages.
Then write a program that will generate a site map of your pages.
Write a web spider.
Write a chat bot.
Write a command shell or a RAT.
Write a program that automates a bunch of command line programs. Say a process take like 50 or so commands in CLI to handle write a program or script that will do it with a command and maybe some arguments.
Write a picture board.
Write a chat server and client.
Just a few ideas off the top of my head.