As long as you're persistent and take the time to learn and master traffic you'll be fine. Don't make the mistake other people make when they try to focus on 10 different platforms at once and get abysmal results. Choose one platform you have the most experience with already and master it, then scale up from there.
You don't even need to try and hard sell, working with you would be value gained for them, so in their minds it's something they want to take. If you push it too much they begin thinking something is up and maybe there's a catch or more to it, etc.