The main ways you're exposed to microplastics is through ingestion and breathing it in.

To limit ingestion, yes the main thing to do is to avoid food and drink that comes in plastic containers. Reducing your consumption of processed foods will help with this. Eating mostly produce is a simpler way to approach this. Even though produce may often be transported in plastic, if you wash it before consumption you'll have done pretty well. Ideally you would also have a reverse osmosis filter at home, as your water probably has microplastics as well (but less than bottled water!).

To limit breathing it in, yes avoid frequent exposure to busy roads. They are often full of tire dust that is getting kicked up. This is cumulative, though. Walking by a busy street once is no big deal. Walking along one twice a day may add up.

Overall, however, to address microplastics we will have to control the production of plastics and the use of plastics in the first place. For example, there would be a lot less tire dust if we used more rail to get around. And there would be less need for bottled water if water fountains were ubiquitous and so were standardized stainless steel water bottles. In addition, we could use biodegradable plastics for more packaging so that they don't accumulate in bodies or the environment.

But this last point, despite being the only real solution, will literally require the overthrow of capitalism. I'm for this and am happy to talk about it more, but it is a lot.