I want to quit my job and work freelance and research...?

If you think you are ready than by all means establish an advertising company. That seems to be the direction you are headed. As a buisness consultant my recomendation is do what you love and love what you do which will always grow your future. God Bless!!! Remember: do not burn your bridges behind yourself, I mean be sure and leave insuring good feelings with all. Always be truthfull and respect all!