I mean after learning all the functions of different tools how should I proceed to master designing? What sources should I go through to have a clear cut idea of logo designing or how I can explore different things that I can do through Adobe Illustrator?
To get a "master level" understanding of any Adobe application, read and study the Adobe Classroom In a Book from Peachpit Press for the application you want to learn.
It's dry, boring, and not very intriguing, but it will cover absolutely every aspect of the application. These are the "manuals" which Adobe no longer provides.
In no instance will this help with creation and ideation. Those are completely separate things. Learning a tool (such as software), has never improved one's ability to create designs. Merely the ability to see one's creations to fruition.
If you wish to improve your design skills... well.. that takes practice and self study or formal education.
Learning all the letters on the alphabet, learning all the definitions on the dictionary, does not mean you can write a "master" novel.
To see the potential of a language, English lets say, you probably need to compare the before and after Shakespeare, to read poems, or better, listen from the lips of an artist in reading poetry, and if is someone you care, the better.
Clicking buttons and menus will not make a logo, an illustration, a "master" pice. Only a few people accomplish that...
Take Illustrator... and turn it off. Now start looking logos, vector-based illustrations, digital paintings...
Now take your computer... and turn it off.
Go to a classic art museum, see a painting, Rembrandt, Velazquez, Goya, Raphael, Leonardo.
Studying "history", not only classical paintings but also the history of graphic design, let's say of poster design, American, Russian European, Art deco, Vanguardism, Aerography in the '80s... is not to illuminate your mind, is to see how people are solving communication problems, using tools available to them. Limited printing capabilities, pallets, techniques and technologies.
Back to the computer. Put objectives on what you do, make a cartoon-like drawing, then do something more elaborate.
See you in some years from now.
I do not mean to say this example is a masterpiece, but I know I feel free to move around vector based programs (and raster for that matter)
A. Make the base shapes. This means observing and deconstructing what you want to do. Imagine them as if you are cutting pieces of paper.
B. Here are the same shapes with a base color. Flat design, logos etc can stop at this point.
Add gradients, but you can do it the wrong way (C) or the right way (D).
C is the result of just adding a gradient assuming you know how things work... and D is actually observing both, real case examples and your own project and results.
That would be a vector-based Illustration.
But you can add some other resources. A vector based program can handle raster images, that you can process somewhere else, mainly Ps or similar programs.
Here I added a bitmap "sperized" And probably this should not be glossy anymore.
When making a vector-based illustration those parts would be essential.
Define shapes, define gradients, transparencies and blending modes.
If you already know well all drawing tools and effects in Illustrator, you obviously also can draw different things with them at least by copying existing works or by working tutorials (you easily find hundreds of them). The next thing is to try to present something by yourself.
Take a pen and paper. Return to graphic software after you have drawn on the paper something which is reconizable, contains some idea which you believe also others see in your drawing and you see it's good enough to be redrawn with sharp solid lines, shapes, texts and colors. It can be a sketch of a thing which exists in front of you, but you do not have already made drawing of it to be copied. A little later it can be an attempt to claim something. Claim = try to show relations and properties, real or artificial or both.
Being able to present humans, animals and their moods is difficult, one can practice years before he can draw them as he likes. Only simplest cartoon-like line drawings are possible in months.
Of course it can be difficult to do it in full isolation. You can start by watching already done works, say advertisements, for example. Try to say the same in other way or try to say something else of the same subject.