If you don't live in the USA, and aren't a US-Citizen, most of the following should apply for you.

Brokerages: People from most countries can set up an account at one of the following:

• ProsperUs (Singapore)
• Philip Poems (Singapore)
• IBKR (USA)
• Standard Chartered (UK)
• Saxo (Denmark)

ETFs: VWRA - this exchange-traded fund (ETF) holds 3,600 stocks from around the world. It holds large, mid, and small cap stocks. It generally covers a diversified representation of the worlds stock markets.

Read: The Millionaire Expat by Andrew Hallam

Steps:

1. Set up a brokerage account. Connect your bank account to the brokerage.
2. Transfer money in by USD to your brokerage account.
3. Buy VWRA in a lump sum every time you transfer money in. Try to do this once you've accumulated at least $1,000 to minimize trading commission costs.

That's about it to get you started.

Note if you're in the UK, buy VWRP with GBP, if you're in the EU, buy VWCE with Euros.