I am writing blueprint in unreal engine but I am a bit new, how can I improve myself and learn new things?
Start by asking which part you enjoy doing the most? That would be your starting point. Can change later by the way doesn’t have to be one 
Even is better when you have multiple interest and depth knowledge, slowly you become more holistic on the problems that you want to solve, entertainment you want to create, it would give you some special powers.
Every discipline has some things visible on surface and hidden nuances not visible to naked eye when you start to go deep in them. Like Graphic design, what makes a good graphic designer?
So if you want to make games, just start anywhere is my advice.
Nowadays everything is super accessible compared to 15 - 20 years ago. Those times you cannot even access an engine if you are not lucky enough Even accessing information is limited about subjects. However on the other side now there is too much content that can be overwhelming at first glance but not all of them are right way of doing things, with a lot of objective opinions even misdirections sometimes. So accessing the right information becomes crucial.
Things do change, world is dynamic so is human. You will see once you start doing anything that you like, it will keep going, your will discover more and do more. Even not everything in game development is hard craft, a big part of it is just design thinking and I see that it is very much missing in major gaming development companies.
Google it
Watch it , Read it.
Replicate it, make it better.
Here is some nice channels that I visit time to time and get some valuable wisdom. I am pretty sure they also do the same. There is no formula to it, like in art, you practice it.
some very nice high level wisdom.
Scope out a project that you are interested in. With out a goal that has interest you’ll get bored, frustrated and quit.
Actually ı learned so much things in a few months ı can make a half game myself but recently ı cant find any answer for things that ım trying to learn.I cant find a good AI tutorial.
Sure thing its possible, its just about scope and dedication.
Here is a nice starting point forr AI basically it can teach you.
AI Controller
Behaviour Trree
Navigation, Tasks, Avoidance, EQS, Pathfinding
not everything is to the end perrfect however its extendable. Sometimes you will want to expand some of the existing systems into AI or you can ground up design like that if thats the intention.
On the video there should be a state switch if I remember correctly for enemy aggressions, agression system can be seperate component or behaviour tree. However just replicating the tutorial will give you a great starting point and learn to tools available.
EX: I have weapons in the world, I pickup and shoot, enemy uses same weapons as well to shoot me.
After learrning the basics its all about keeping organised and having fun with creating nice bosses.