If you can, start to build up a 'device lab' of older devices (phones/tablets) to view your work on. Having a number of varied devices is hugely beneficial. Not only does it let you feel how a design actually works across different devices, it also exposes layout/rendering peculiarities earlier in the process. After all, no one enjoys believing they have finished on a project to be told it doesn't work properly in a certain environment. Test early, test often! It need not cost the earth. For example, you can pick up older phone and tablet models on eBay, or buy them from friends/relatives as they upgrade.