A good quality synthetic brush that is a suitable size for the project will increase drying time and reduce brush marks. Alternatively, a roller will help you get the product on quicker and avoid brushmarks, however it will give a slight orange peel effect. Use the correct specified roller for water-borne products, do not use a foam roller as this could cause aereation (bubbles).
Lightly dampen the bristles of the brush before use. This will provide added application time (wet edge) as it helps paint to flow more evenly from the bristles.
Wash your brush every two to three hours. This will prevent paint from drying in the stock of the brush.