Are there any MUST KNOW techniques or operations on Blender that i should consider using when im modeling?
Right now im modeling almost everything with extrusions, bevels, insets, spins and very basic operations.
I’m feeling like im using 1% of the Blender features…
You forgot edge loops, but yeah, those tools are considered the basics for a reason. They’re what you tend to use the most until you start getting into higher res meshes.
I’ll occasionally jump into sculpt mode, and use the grab tool to shape things up if I’m working with something a little more organic, but more often than not, it’s edge loops, extrusions, bevels, insets, spins, and so on…
A couple of others would be all quad as much as possible and be careful of 6 pointed stars (vertices with more than 5 connected edges), especially along the center line of a mirror. But as far as operations, those are the most used. Think of it this way. … A master is a master of the basics. Because even at an advanced level, you are still using the basics you used when you first started.
I’d add hide and unhide into the mix. It’s not exactly a modeling tool, but it often helps when you have some tricky bits that are hard to get to. And the “F” key to make a face or an edge from selected vertices.
You are using about 1% of Blender’s features, and that’s OK. Most of the additional features were added because, in certain situations, they might speed up somebody’s workflow. Quite frankly, some of the bells and whistles were simply added because other 3D modeling software had the feature, and Blender devs didn’t want to lose face. (Don’t tell them I said so, because they are sure to come back with “But you simply can’t do x operation without y feature!!!” which is true, but if you don’t do x operation, what’s the point?)
The real trick in learning complex software like Blender is discovering what you can safely ignore. If you can model the things you want to model with the tools you know, you’re golden. Every now and then, take a look at some tool specific tutorial to see what it does and how it works, and think whether you need it in your tool box.
Welcome to BlenderArtists 
The knife tool (k),i use it allot to create supporting loops on complex meshes or to fix ngons.
Also,welcome to BA.
Thank you guys.
I already knew about loops and hiding but thank you anyways, i really appreciate the support.
You guys made me way more confortable. I felt like i wasnt improving after some months of Blender since i was using the same actions over and over.
The one i have to try is the knife tool. I think this one will help me a lot.
Also, thanks for the welcome 
Everyone models differently. It’s the model requirements and knowledge of polygonal modeling that shape the result despite of different workflows.
The goal is not to know everything about the software but enough to form workflows for solving bigger and smaller modeling problems. Usually there are multiple solutions that each require a subset of tools to be used. Once you learn about a new tool, it’s then possible to form an idea on how it can affect the workflows you already are familiar with, or form new ones. Could also test it with a workflow in mind.
Learning doesn’t stop and the workflows get adjusted more or less when the tools change or more becomes available.