All property developers make their money when they buy, not when they sell.
The cost of borrowing has made BTL mortgages almost impossible, but if you can get together with family or friends to buy for cash, there is still money to be made.
You will need to research your area and target audience very thoroughly, but provided you can buy cheap, as Gnome says, your rental yield can be very respectable, at least versus money in the bank. Buy location first, then somewhere dated but habitable that needs only a good clean, a lick of paint and a decent letting agent. People buy wrecks because they think they'll "add value" with the renovation, not realising the tax and VAT implications, or that fees and trades will wipe out profit.
Auctions are not your friend since everyone and his dog started watching Homes Under the Hammer.
As Noddy says, it's very difficult to "add value" to a property unless you have a practical skill or particularly good contacts. You don't necessarily need a trade though - being familiar with financial instruments or demographic analysis is probably just as useful and cost-saving as, say, plumbing.