For many investors who have enjoyed heady stock gains in 2017, "taking a little money off the table might not be the worst thing in the world to do," says JJ Kinahan, chief market strategist at TD Ameritrade, in a CNBC interview. Additionally, Kinahan advises investors to review their asset allocations, which may have shifted dramatically as some industry sectors or asset classes raced ahead of others. "If you're overweight in certain sectors such as technology, your portfolio might be a little bit out of whack as to what your goals are," he told CNBC.

The S&P 500 Index (SPX) is up 19% for the year-to-date through Tuesday, per CNBC, and had a trailing P/E ratio of 25 as of December 8, per calculations by Birinyi Associates as reported by The Wall Street Journal.

Be Selective

"Technology still does have some room to grow," but investors should be selective, Kinahan's told CNBC. He also mentioned energy and financial stocks as areas where investors may find value. With energy, he sees stability in crude oil prices. With financials, they stand to be major beneficiaries of tax reform. Energy stocks "currently trade at a 32 percent discount to fair value," writes Jim Paulsen, chief investment strategist at The Leuthold Group, per a research note issued earlier this week, as quoted by CNBC.

Cheap Energy

Among large cap energy stocks, for example, these five have low trailing P/E ratios relative to the S&P 500: Canadian-based Imperial Oil Ltd (IMO), P/E 16; French-based Total SA (TOT), 18; Valero Energy Corp. (VLO), 19; Marathon Petroleum Corp. (MPC), 20; and Canadian Natural Resources Ltd. (CNQ), 20, based on Morgan Stanley's (MS) stock screener.

Low Cost Financials and Tech

Within the tech sector, Kinahan advises buying on a selective basis and urges caution with chipmakers, whose recent sales increases have been tied closely to gaming or the mining of bitcoin. He believes these drivers are "plateauing," per his remarks to CNBC. Within the tech sector as a whole, these two stocks have the lowest P/E ratios among large caps with overweight ratings from Morgan Stanley: semiconductor manufacturer Micron Technology Inc. (MU), P/E 10; and International Business Machines Corp. (IBM), 13.

Among financial stocks, these four have the lowest P/Es among large caps rated overweight by Morgan Stanley: insurer Athene Holding Ltd. (ATH), P/E 7; banking and securities firm Grupo Financiero Santander Mexico SAB de CV (BSMX), 11; consumer finance company Discover Financial Services (DFS), 13; and Goldman Sachs Group Inc. (GS), 13.