How do you convey your idea when you can't convey your idea? I am PhD student works in a computer science. I have given lots of presentations in the institute level and one or two at the conference level. I have been told by my fellow researchers that they did not get much from my presentations/talks. Even I have presented one paper in the conference also and got the same feedback. I spend more time on making slides as well practise at least two three times on the projector also. I think I am kind of person who is worst at presenting the work. Assuming this Is there any way through which I can deliver a good talk?
I'm also not great at presenting. One method I've found useful is to present to and get feedback from people who have around the same level of knowledge as your intended audience (i.e. people who are not too heavily involved in your project, but are in your research field). This means they will be able to tell you which parts you need to explain in more detail. 

Also, look at other people's presentations to see what's the standard level of technical detail in your field - I've seen presentations where the focus should be on the scientific analysis and results, but instead too much time is spent on the minutia of how the analysis was performed.