The proven Zacks Rank system focuses on earnings estimates and estimate revisions to find winning stocks. Nevertheless, we know that our readers all have their own perspectives, so we are always looking at the latest trends in value, growth, and momentum to find strong picks.Looking at the history of these trends, perhaps none is more beloved than value investing. This strategy simply looks to identify companies that are being undervalued by the broader market. Value investors use fundamental analysis and traditional valuation metrics to find stocks that they believe are being undervalued by the market at large.Luckily, Zacks has developed its own Style Scores system in an effort to find stocks with specific traits. Value investors will be interested in the system's "Value" category. Stocks with both "A" grades in the Value category and high Zacks Ranks are among the strongest value stocks on the market right now.One stock to keep an eye on is Tilly's (TLYS). TLYS is currently sporting a Zacks Rank of #1 (Strong Buy), as well as an A grade for Value. The stock has a Forward P/E ratio of 9.16. This compares to its industry's average Forward P/E of 15.46. Over the past year, TLYS's Forward P/E has been as high as 20.94 and as low as -78.88, with a median of 15.29.Another notable valuation metric for TLYS is its P/B ratio of 2.48. The P/B is a method of comparing a stock's market value to its book value, which is defined as total assets minus total liabilities. This stock's P/B looks solid versus its industry's average P/B of 5.50. Within the past 52 weeks, TLYS's P/B has been as high as 3.01 and as low as 1.23, with a median of 2.20.Value investors also use the P/S ratio. The P/S ratio is is calculated as price divided by sales. This is a prefered metric because revenue can't really be manipulated, so sales are often a truer performance indicator. TLYS has a P/S ratio of 0.63. This compares to its industry's average P/S of 0.74.These are only a few of the key metrics included in Tilly's's strong Value grade, but they help show that the stock is likely undervalued right now. When factoring in the strength of its earnings outlook, TLYS looks like an impressive value stock at the moment. More Stock News: This Is Bigger than the iPhone! It could become the mother of all technological revolutions. Apple sold a mere 1 billion iPhones in 10 years but a new breakthrough is expected to generate more than 77 billion devices by 2025, creating a $1.3 trillion market. Zacks has just released a Special Report that spotlights this fast-emerging phenomenon and 4 tickers for taking advantage of it. If you don't buy now, you may kick yourself in 2022.Click here for the 4 trades >>Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report Tilly's, Inc. (TLYS): Free Stock Analysis Report To read this article on Zacks.com click here.