Which things are most important for graphics freelancing and what is the thinking subject for a logo poster and banners design.
I don't understand your pol question. However, to answer your thread, you probably need to work on some projets while in school or teaching yourself techniques via online tutorials. Then, get feedback from people to find out what they think looks good.
technically nothing is important for that.. if any thing important that is ur mind imagination, ur creativity, how u repreasent ur work..etc
Your question was a bit difficult for me to understand, so sorry if I'm answering incorrectly, but: The most important thing for getting clients (besides talent and reputation of course) will be your portfolio, ideally just a couple examples of your best work for clients to see. When I was first starting out and couldn't find work to build my portfolio I started looking for not-for-profit organizations and companies I liked and sent out a bunch of e-mails asking if I could design them something for free in exchange for me to use it in my portfolio, most people seemed happy to get a free logo and I felt great helping numerous causes! For the thinking behind a logo, that can be pretty much anything when you have the technical skill to make. At first I would use other logos for inspiration (NEVER actually copy anyone, but draw influence from your favorite designers). Now, several years into it I find inspiration from architecture around me, I see colors in nature and photograph them to use the colors later, even music. I hope this helped you a bit on your artistic adventure!
From my experience you need to develop a base in digital drawing and adding effects for animated banners and cool colors for simple banners and Logos.
Best mantra for graphic designing is create your own designs and present innovative designs to get maximum projects and appreciation.