How do you find the best and simplest model given a table of data? I know how to find a specific regression (linear, cubic ect...) but i'm lost when it comes to choosing the best one.
It depends what you mean by best.
If you have n discrete points, you can always make a polynomial curve go though every single point by using order n-1.( Two points - straight line order 1, Three points - parabola order two, Four points - cubic, order three etc.) That is probably not what you want in a real world problem with many points because the higher the order the bumpier the curve (straight line - constant direction, parabola first up then down, cubic up- down - up etc). In other words you need to choose your model based on what is appropriate for the type of problem you are working.