Picking stocks is easy. Picking stocks that are smart choices, though, is more challenging. And doing so with a limited amount of cash to invest makes it even harder.

All of that is true, even with dividend stocks. It's not advisable to merely scoop up any stock with a high yield and a low share price. But there are good opportunities to be found. Here are my picks for the smartest dividend stocks to buy with $400 right now.

1. Brookfield Renewable

You can buy four shares of Brookfield Renewable (BEP 0.19%) (BEPC 0.09%) for less than $130. I believe it's an investment that will pay off nicely over the long term.

Brookfield Renewable operates hydroelectric, wind, solar, and distributed energy facilities across the world. Its current capacity is 32 gigawatts. But the company's pipeline capacity is more than 4x that amount.

There's a good reason why Brookfield Renewable has such aggressive expansion plans. The demand for renewable energy is expected to skyrocket as countries scramble to reduce carbon emissions.

Brookfield Renewable expects to deliver average total returns of between 12% and 15% per year. A big part of that total return will come from the company's distributions. The distribution yield currently tops 4.2% for the corporate entity shares trading under the BEPC ticker and stands at 4.5% for the limited partnership units trading under the BEP ticker.

2. Enterprise Products Partners

It will cost you less than $110 to pick up four shares of Enterprise Products Partners (EPD 0.45%). And you'll quickly start to benefit from the company's juicy distribution yield of nearly 7.4%.

Those distributions are likely to rise over time, too. Enterprise has increased its distribution for an impressive 25 consecutive years. That trend will almost certainly continue, thanks to the company's steady cash flow.

Enterprise Products Partners operates over 50,000 miles of pipeline in the U.S. and Canada. It runs 29 natural gas processing plants and 25 fractionators that separate hydrocarbons. The company also stores liquid fuels and owns deepwater docks.

The long-term prospects for natural gas and natural gas liquids -- Enterprise's primary areas of focus -- remain robust, despite the increased use of renewable energy. However, Enterprise's share price doesn't reflect this.

The stock trades at a forward earnings multiple of only 10.4x. This valuation combined with Enterprise's exceptional yield make it a great pick right now.

3. Pfizer

After buying four shares each of Brookfield Renewable and Enterprise Products Partners, you'd still have over $160 remaining from your initial $400. That's more than enough to buy four shares of Pfizer (PFE 0.55%).

At first, glance, investing in Pfizer might not seem like a smart move. The big-pharma stock has performed dismally this year. Pfizer's revenue and profits have also declined as a result of sinking sales for its COVID-19 products.

I think, though, that Pfizer is a diamond in the rough. The stock is cheap, with shares trading at 11.2x forward earnings. More importantly, Pfizer should return to strong growth over the next few years with new product launches, business development deals, and rebounding COVID-19 product revenue.

In the meantime, you can get paid quite well to wait for the turnaround. Pfizer's dividend yield currently stands at nearly 4.4%.