Before viewing properties, compare the different yields. The yield is the annual rent received as a percentage of the purchase price. i.e. a property providing £1,000 monthly rental (£12,000 per annum) on a property valued at £250,000 has a 4.8% yield. Be aware that this is a gross yield – you will have other costs to take into account including tax
Rent should be the key return for buy-to-let. Most buy-to-let mortgages are done on an interest-only basis, so the amount borrowed will not be paid off over time. If you can get a rental return substantially over the mortgage payments, then once you have built up a good emergency fund, you can start saving or investing any extra cash.