With shale oil an increasingly important source of cheap energy, particularly in the U.S., Rubenstein also recommended looking for investments in carbon energy.
"I think carbon-related energy is a great opportunity, because of what is going on in the United States, the energy revolution and the enormous demand for energy in the emerging markets," he said.
In terms of regions, Rubenstein said that Europe was at its most attractive in half a decade. He added that Carlyle had done around nine deals in Europe in the last 12 months, spending roughly 1 billion euros ($1.4 billion).
"We think Europe has been overlooked; Europe is cheaper than the U.S. in terms of comparable assets. People abandoned Europe as a place to invest because of the recession, but now we think it is a more attractive place to invest than at any time in the last five years," he said.
(Read more: Bubble watch: Blackstone exec on housing health)
Despite the recent turmoil in emerging markets, Cambridge Associates Director Miriam Schmitter said that opportunities existed in the sector, although no country was a "screaming value buy".
She highlighted sub-Saharan Africa. "I think that's a very exciting market. South Africa is almost a contrarian value play; I like that market," Schmitter said.
"Other places like Latin America or China have been moderating; prices have been cooling off, so they could be interesting as a position for the next 10 years," she added.
—By CNBC's Katy Barnato. Follow her on Twitter: