Various stock markets are close to all-time highs. The S&P/ASX 200 Index (ASX: XJO) is close to its recent all-time high, with many ASX shares at a higher valuation.

The global share market has also been reaching all-time highs. Just look below at the unit price of the exchange-traded fund (ETF) Vanguard MSCI Index International Shares ETF (ASX: VGS).

Finding opportunities can be trickier when asset prices are high. Buying things at appealing prices can usually give us a better margin of safety. But what are we supposed to do when there's less margin of safety?

In my mind, there are three ways to go.

The entire ASX stock market doesn't move in unison – if the ASX 200 goes up 1%, it doesn't mean every single business has gone up 1% – some will have increased by 2% or 3% and a few may have gone down. We can still find opportunities among the expensive valuations. There are always some companies that are being underpriced, in my opinion.

I think the recent strength of the ASX 200 has been driven by the ASX bank share sector, including Commonwealth Bank of Australia (ASX: CBA), Westpac Banking Corp (ASX: WBC), ANZ Group Holdings Ltd (ASX: ANZ) and National Australia Bank Ltd (ASX: NAB).

Plenty of businesses with good growth prospects aren't at all-time highs. I've been looking at companies like Johns Lyng Group Ltd (ASX: JLG), Metcash Ltd (ASX: MTS), Close The Loop Ltd (ASX: CLG), Accent Group Ltd (ASX: AX1) and Brickworks Limited (ASX: BKW).

I'm not going to call ASX iron ore shares great opportunities at this stage, though their share prices have fallen amid a decline in the iron ore price. If/when the iron ore price goes below US$100 per tonne on a sustained basis, that could be a more appealing time to invest in names like Rio Tinto Ltd (ASX: RIO) and BHP Group Ltd (ASX: BHP).

If we can't decide on a particular business to invest in, it could still be a good option to invest in the share market as a whole and hold the ETF for the long term.

The VGS ETF has hit numerous all-time highs over the past decade – it would have been a mistake never to invest just because it had reached an all-time high in 2017. Of course, there has been volatility along the way, but rising profits have helped push share prices higher over time.

I'm not saying the global share market is great value today, but I believe the long-term is still promising.

I'd be willing to invest in the VGS ETF, as well as other ASX-listed ETFs that I think have appealing capital growth potential such as VanEck Morningstar Wide Moat ETF (ASX: MOAT) and Betashares Global Cybersecurity ETF (ASX: HACK).

The last four years have shown that volatility for the (ASX) stock market is usually never too far away. We don't need to rush investing, we can be patient and wait until we find something we like.

Earnings can grow, and/or there could be a fall in share prices in the future.

Warren Buffett, one of the world's greatest investors, has said some wise things about this:

The stock market is a device to transfer money from the impatient to the patient.

Buffett also once made a comparison between baseball and investing, making the point that you don't need to swing at every pitch. He said:

The trick in investing is just to sit there and watch pitch after pitch go by and wait for the one right in your sweet spot. And if people are yelling, 'Swing, you bum!,' ignore them.

Being patient wouldn't be a bad thing at all with ASX shares.