To adjust the table gibs on my mini mill I move the table to the middle of the X axis and set a dial indicator measuring horizontal play at the end of the table. I then lock Y and loosen all the X set screws. I adjust the two outside set screws until I have about 0.0015"-0.002" of measured play in the table. I then adjust the two inside set screws individually by tightening them just until I feel resistance in the hand wheel, then easing them off just slightly.
For the Y axis I lock the X and loosen on the Y set screws. If you have only two Y set screws then adjust them until you have about 0.0015"-0.002" play in the table. If you have four set screws then adjust the two outside ones until you have about 0.0015"-0.002" play, and then individually adjust the two inside ones same as on the X axis.
When you're machining, be sure to lock all the axis except the one you'll be moving.