bugra malsin

This is a very well done portrait, good color choice, fun pose and good emotion all wrapped in a very nice style that suits it all very well. The simple background does a great job of contrasting with the blue of the scarf and metal as well as interracting and harmonizing with the tans and browns of the skin tones, hair, recorders and leathers. The subtle, but very well defined, highlights go a long way in pushing the form of the character as do the thin dark blue outlines. All around I'd say that this drawing as a whole has an excellent sense of form and weight to it, that being said the armor and the scarf are shaded in very similar ways, which makes them feel a bit like they are made of the same material. Maybe pushing the highlights and shadows on the metal a bit more will help with that, I'm hesitant to say do anything to the cloth because I really like the way it is realized as is.
One of the most noticeable issues with this is the way the colors occasionally dip outside of or don't fully cover the inside of the blue outlines which does a lot to undermine their purpose, it's tedious but sitting down and working it out may be worth it. Also on the scarf those two reddish-brown folds don't fit too well since that's the only place that color occurs in the drawing, ditching them all together would probably be the easiest way to go about it. Before I forget, those hands are very well done and great to look at. Back to it - the highlights on the cloth on the (our) left shoulder and on the right edge folds opposite of that are not very convincing. As a rule of thumb don't use white in a way like that to do highlights, mix it with yellow or whatever the light source's color (in this case the background color) is and mix it into what is being highlighted, it will make for a more unified sense of light and interesting color pallet. I really like the highlights on the left and right side of the head, they're great for the for, and have great colors in themselves.
You mentioned that you're interested in more effective methods of using color and my friend, that is a deep rabbit hole to go down, I took a color theory class last year and the first thing the professor said was "the more I learn about color the less I know about it" and I believe him on that. There are countless ways to use color and color combos to convey information and this drawing has a very straightforward use of color and for this style it is very well suited. Though a few key things to keep in mind for future use of colors beyond complementaries, tint, tone and shades is that yellow is your brightest and violet is your darkest. When used in small amounts I find using violet tints, tones and shades to be very effective in bringing out shadows while still creating interest and not just going the darker shade or adding black. I'll probably drop by your thread and give you more color advice as you continue to post since it really is hard to be brief about possible combinations and interactions. If there's anything in particular you need assistance with feel free to message me, I don't know everything but I am pretty good with colors, but as always the best way to learn is through continued experimentation, so keep at it and you'll be a-okay.

I am a fan of yours for life because of this.
https://www.youtube.com/watch?v=C6OmnTWhsEc