How does increasing the polarity of the solvent system affect the results of a TLC?

mainly the interaction of analyse and the base comes in mind and that way how solvable it is. if you but ethanol in water there is a change that it's blocking the space between the base and water and so on also let's other substances be carried away. so basically it would give lower distance for more polar and vice versa. also what kind of base are you using if it's selective for some substances