Check youtube for guides, I just replaced the lcd/touchscreen of my Nexus 4. £35 in parts and did it whilst dinner was simmering on the hob. And my replacement screen came with the chassis which meant I avoided having to heat the old screen with a hairdryer to release it from the chassis, but did have to unplug and transfer every single component from the motherboard and chassis.
It was fairly easy, as long as you have some mechanical sympathy for unplugging the delicate ribbon cables etc you should be fine.
If your phone has a non-removeable battery, it might be worth buying a replacement. Mine was only £8 and glad I got it as the soft Lipo battery is fairly mangled after unsticking it from the chassis, wouldn’t trust it and it went outside in case I’d damaged it internally.