Thanks for all your replies! I really appreciate your comments, Krarl, amplitudeproblem and San Dingo, and it is great to hear, that some of my tracks could fit the theme
I will read through the sticky post with direction of music explained and I will listen to trillek group on soundcloud at the weekend and I will try to compose something that would answer your question, amplitudeproblem.
To answer another question of yours, yes I cut unnecessary frequencies particularly in bass section, however, my studio equipment is not top-of-the-line, unfortunately, so I am aware that there could still be some mixing/mastering flaws when it comes to bass or mid-section (sometimes because I simply don't hear those flaws on my equipment). But it can be harnessed - based on my experience and your help, we can work out to mix it so it matches the rest of the tracks from the soundtrack and has consistent final sound as you stated.
As for the tools I use, I work in FL Studio DAW, using various VSTs that came with the Signature Bundle and some other VSTs I acquired along my way making and learning music. I edit sounds or make them from scratch, I compose all the notes, bassline, melody, beats etc. by myself using built-in pianoroll in FL Studio. For final mixing I use my hi-fi equipment (yup, I know I should have studio monitors and dedicated audio interface or at least good pair of studio headphones, but I can't afford them now).
If you have any more questions, shoot - I will answer them with a pleasure