Be independent as much as you can.
By that, I mean that the most successful artists I have met do not work exclusively/solely with one gallery or agency; they are in control of their art career and their work.
At the same time, they do not associate themselves with too many organizations or galleries – they are careful.
Whilst it might be tempting to sign with a gallery or accept work from so and so company, you must think long term. Who you are associated with professionally reflects on your career long term. Every exhibition, award, achievement and event can certainly enrich your career, but it can also hinder it.
So, basically the Tips are: stay true to yourself; stay in control of your career; allow yourself to be picky when working with people; do not become exclusive with any one gallery/company and when working with art agents too.