Here are answered the questions I receive the most often.

I used to use Gliffy. Now I use InkScape.

From 2004 to 2014, I used GentleSource comment system with Akismet to detect bots and spam.
From 2014 to 2018, I used Disqus.
In 2018, I took everything down because it added little and consumed a lot.

1. Read the source code of a shoot-em-up: They are easy to understand. Prototype won first place in the first shmup-dev competition. You can find the full source code and assets here. If C/C++ is too scary or you are more used to GC environments, you can read my Java version.
2. Write a shoot-em-up: Use Prototype's sprite assets and let your creativity go wild. That's how I started.
3. Read books. Mr Elusive (Jan Paul van Waveren from id Software) has a list of the best books: Read all of them.
4. Read good game engine code: The code reviews on this side are good starting points.
5. Practice and write a more complex game. Language doesn't matter, the important is to attempt to emulate yourself.

I wrote an article recommanding the best books about C. You can find it here.

I have a love/hate relationship with it. I like the design philosophy to never make you pay for what you don't use. I love to be close to the metal. I hate that it is such a rich environment that some developer can write code that almost nobody but themselves can read. It is the only popular language for which I have never met a "guru". By this, I mean a person able to read anything and understand it right away. Especially when meta-programming is involved the thing can become an unbearable pain to read.