Use the minimum number of slides that will allow you to convey the essence of your paper to your audience. You have 45 minutes for your presentation. Experience tells us that most SNUG talks do well with between 15 to 20 slides. An outline of your major topics should be your second slide, just after your title slide. Line graphs show trends or correlation effectively.
Pie charts are good for showing relative parts of the whole.
Symbolic diagrams and flow charts are useful if not too detailed. Use standard symbols if possible. Simple schematic diagrams effectively convey the structure of systems or relationships of objects. Show only what is necessary to explain how a thing works. Tabular data is more legible and more easily compared on graphs or charts.