What material is your table made of? Some cleaning products you can't use on wood. Is it dirty from use or has something spilled on it? More information would be helpful to specifically address your question.
Warm water and dish soap is your safest bet. Without knowing the type of table (wood, type of finish, etc.), it's difficult to recommend a more specific cleaning solution.
If your table is made of wood, remove all dust and grease with a damp rag and apply pledge or other cleaners especially developed for wood. Avoid excessive water and abrasive sponges or you will damage the wood. Good luck!
Depends on the type of table you have.
It all depends on what it is you want to clean off and what the table top is made of and if it has a top coat. I use warm water on mine, but it is covered with multiple coats of polyurethane. I would avoid pledge or anything like it that will cause build up that is not easy to get off. Wash wood off and make sure to dry it with a soft cloth. If it is laminate, use as little moisture as possible to avoid damaging the surface.