If you are trying to understand the dissolution process in general, you should stick with using table salt since the particles are smaller and will therefore dissolve easier. If you need to study the properties of a specific salt, use that salt.
This is because there are fewer water molecules interacting with other substances in the water, and therefore, more water molecules free to dissolve the salt.
You can add salt slowly to see approximately how much can be dissolved in a given amount of water (at a given temperature). You can dissolve more salt by adding more water or heating it up.
Make sure to label your container, especially if you are working in a lab with other people.
There is more space between the water molecules if it is at a higher temperature, which is why it dissolves salt better. Cold water has less space between the water molecules, so less salt fits in between them.
