How do you check whether your fund fees are eating into long-term returns?

For a beginner, fees can feel like a small detail next to the excitement of picking investments. Yet an expense ratio is charged every year, whether the fund does well or poorly, so its effect compounds over decades. A difference of a fraction of a percent sounds trivial until you run the numbers over twenty or thirty years. When I look at a fund, I find it useful to read the expense ratio, then look for any other costs the fund reports, such as trading costs or sales loads. Comparing two funds that track similar indexes is a good exercise because the holdings are nearly the same and the cost difference is easier to see. I'm not certain how every fund reports these costs, so reading the most recent prospectus or shareholder report is worth the time. I'd be curious how others approach this in practice. What do you look at first when comparing funds, and how far out do you project the effect of fees?