I have completed all the projects in “Getting Started for Beginners”. Where can I find more or more advanced projects?
Do you have your own project in mind ?
The internet is a vast place and simply adding "arduino" to a project search often brings good results.
Just try to expand on your current knowledge or even merge two different simple projects to see how you get on.
Er well in mechanics you have a "spanner". You can do with it as you will. If you have done, and understood, all the starter stuff then you have a good grounding in doing whatever you want. So what would you like to do?
There is a steady stream of projects posted that need help. You can develop your skills by helping solve the posted issues until you find your own project.
I have no idea what "Getting Started for Beginners" is or what it covers. A link could be useful.
Below some things that I can think of; no advanced projects but trying to advance your level of knowledge.
Work your way through the examples that come with the IDE; some stuff might be duplication of "Getting Started for Beginners" but you might see some new things.
Combine examples from the IDE or "Getting Started for Beginners" and make them work.
Take the StateChangeDetection example that comes with the IDE and rewrite it to use a non-blocking millis() based approach instead of delay(50). Post the result here for us to check if you understand the principles.
Take the Debounce example that comes with the IDE and rewrite it make use of a function that does the debouncing. Next expand it to use two buttons, preferably using a single function.
Start studying C/C++ to gain a deeper knowledge what it can do.
Have a look at the Useful Links Thread.
There is loads more on the Arduino main site, enough to fill a decently thick book.
To get you started;
Good idea is to go through the Foundations pages and see if there's anything you missed.
A large source of how-to and what-to articles and projects. Wanna roll your own capacitive sensors?
A good thing to do is to make an easy to get to Arduino folder in your bookmarks and put good links in there. Whenever you run the Arduino IDE, also open a web browser with the Reference Page in the first tab and any other pages you need in other tabs. That way you can fast-check anything you have the slightest doubt about before putting it into your code... it beats the extra debugging that guess-code generates!
The Arduino Reference Page has links to the Libraries and Glossary.
The LibC modules page, these are the standard C libraries that the Arduino IDE uses.