Here are a few pointers to help you get started.
How much do you want to spend on a new smart phone?
The cost of flagship phones seems to increase year on year however if you don’t need the latest model you may find you can purchase a good smartphone for around £150. If you do have a big budget you could consider top of the range show-stoppers like the iPhone 6S or LG G4 however there are some great models like the 4G-enabled Motorola Moto E (2015) available at the fraction of the cost.