You could try to make a non-trivial application in C, such as something using IPC / sockets. You could try to make a game. You could try to make a UI applicatio

You could try to make a non-trivial application in C, such as something using IPC / sockets. You could try to make a game. You could try to make a UI application using GTK or similar UI framework. You could start contributing to an open source project (there are so many official GNU C projects). You could try to write a server that implements a simple protocol from the RFC (such as socks5)[0]. Also look into C build systems like cmake or autotools. [0] https://www.ietf.org/rfc/rfc1928.txt https://www.ietf.org/rfc/rfc1928.txt