Where To Start Collecting?

If you are looking for cheap world coins, you don't have to worry about fakes.

But honestly, figure something you find interesting and just do it for a few weeks or months, with some moderation (don't run out and buy $100k worth of coins).

If you want a cheap modern challenge, OFEC. One From Every Country. You can define "every" - maybe countries issuing coins dated 2000 or later. Maybe every country in Europe that uses the Euro.

You can buy "poundage lots" on ebay, which will mostly be near-current aluminum and bi-metallic coins.

The Olympic series of British fifty pence pieces might be a good place to start. There's plenty of them,one or two rarities, and lots of information about their designers, some of whom have done other coins. There are also a couple of British £2 coins that mark the handover to and from London. British decimal commemoratives have gone a bit silly lately cos the Mint is running short of work. The thing is, as you're looking things up you'll see other avenues opening, like the 50p is seven sided, so is the 20p but with a thick rim, and coins with thick rims were minted by a chap in Birmingham back in the 1790's, who also made blanks for certain American coins... Above all, have fun!