As an artist you have to find your audience. I think it’s important to stay in touch with your peers when you finish art school. They provide a good support network and as a group you are always stronger than alone!
Don't rely on someone knocking on your door - you have to create your own opportunities. Curate your own shows, participate in open studios, enter competitions, ask if you can show your work in non-conventional spaces. If someone (another artist/curator/collector) suggests you get in touch with a gallery/curator - do it! Don't be too proud but don't sell yourself short. I'd say always err on the side of doing something rather than not doing it - it's better to get your work seen than have it clutter up your studio.
Group shows are great fun because they offer an opportunity to see what your fellow artists have been working on. Showing with known artists helps provide a context for your work and allows curators/galleries/collectors to understand your position. When I organise group shows, I’ll have a theme and I'll be ambitious about the artists I approach to participate. Curating your own shows often opens up other doors, too, because other artists will invite you to participate in their group shows.
It’s also possible to secure exhibition space for free, for example, when a building becomes empty. One of my favourite examples is a project I did called Concrete Allotment Projects, with artist Kristen Lovelock, at a former East London gym. The show was detox-themed and we ensured that this theme ran through the whole exhibition. We had artists exploring detox/toxicity in a number of ways and had sponsors appropriate for the theme. Artists such as Rainer Ganahl, Martin Maloney, Agathe Snow and Oriana Fox all agreed to participate.