I would like to start to develop (while I study) my own cryptocurrency, [...] I forked ethminer [...]
Forking another project and modifying it is not going to help you learn much and if you continue down this path the end result will be the copy of that project inheriting all its issues too and you won't have a good understanding of
why things are the way they are.
For example you need to be able to answer why Keccak was used and why is PoW designed this way with uncles,etc. and what are the disadvantages of this approach?
Can you guys help me telling me the right way to start in this crypto world? What I have to study, examples of codes, wikis, new projects that I can keep an eye, etc.
If you want to
learn and not just create a copy-coin then my suggestion is that you should start from Bitcoin and you don't need to look at the source code that much. You have to study different parts and understand
why every decision was made the way it is.
I say Bitcoin because it has the best documentation and you can find the most amount of content on the internet without needing to read the code. Other altcoins usually have nothing apart from their source code.
For example I would split the whole topic into different categories like this:
1. CryptographyThis includes asymmetric cryptography (ECC in bitcoin) and hash algorithms.
The questions you need to be answer are: What cryptography functions are used in bitcoin, where and why. For example double SHA256 is used in PoW because it is a strong hash algorithm and has a good digest size (not too small to make it weak anytime soon and not too big to waste space).
What alternatives could you be using (eg. could you use Blake?).
2. BlockchainThis includes Proof of Work, structures used for blocks, transactions and finally scripts.
You have to be able to answer questions like why do blocks or transactions look the way they do, what are the issues and benefits of each.
What are scripts used for and why are they designed this way, what is a better way of doing it and what is worse?
3. P2P communication protocolThis includes the way the entire network is shaped and how each client communicates with others and how it contributes to decentralization.
After you had a good understanding of the above, you can start looking at what others have done and see what advantages and disadvantages their approach had.
Sources you could use are:
Bitcoin wiki:
https://en.bitcoin.it/wiki/Bitcoin developer's reference:
https://developer.bitcoin.org/reference/Bitcoin SE:
https://bitcoin.stackexchange.com/Mastering Bitcoin book:
https://github.com/bitcoinbook/bitcoinbookSource code is only useful when you want to figure out the details not to learn:
https://github.com/bitcoin/bitcoin/