The tip of a headphone plug broke off in my 4S's Jack. Despite every attempt to remove it, I was unsuccessful. I determined that I would need to replace the whole jack.
The whole process took about an hour and a half, I went very slow so your mileage will vary. The hardest part was removing the battery. It was surprisingly flexible and mushy. I used the larger Plastic Opening Tool for this which worked well.
After all was said and done, I had a working iPhone and a headache from staring at such small parts for so long.
Spend the money and get the Plastic Opening Tools! They made it much easier to remove little parts and pieces that I would have probably broke without them.
A good pair of tweezers is VERY helpful.
I used a piece of tape(sticky side up) attached to a piece of paper that I stuck the screws to as I removed them. I would then write on the paper next to the screws the step number that corresponded to the screws.
Also, don't be afraid of the flexible battery. Just be careful to not puncture it.