As mentioned above by some of the members.
Bear the following steps in mind
1) The first thing to do is to watch a video on the replacement process and understand it properly, sometimes it helps to watch a few videos as the quality of the videos and the angles used is important in visualisation
2) Have a clean surface with the device on the inside of the desk i.e. not near the edge where you can loos screws
3) Print out a Screw location guide for the iphone which you can find using google as all screws are different and ideally you want to put everything back together as it was
4) Where possible use only plastic tools to remove connectors etc as some of the components are quite fragile and may come of if you use a metal tool
5) Once youve removed all the components you will notice you will need to release 10 screws to get the screen of 4 of them will be small screws in each corner and the other 6 will be in the middle with washers. My advice is take the 4 out of the corners but the other 6 only need to be loosened as they are a pain to put back and very time consuming
6) Finally once these screws are out use a hairdryer to warm up the front of the screen for about 20 seconds youll find the screen comes of much smoother and quicker