This is mainly for beginners. Masters usually have their own adjustments. I'm a novice too, so your advices are appreciated.

Two week ago, i baught a rubik cube on geartaker.com.
vid: http://www.geartaker.com/magic-cube?utm ... magic-cube
It was a little tight. I guess maybe the sellers tight the cubes to ensure its complement during the delivery.

If anyone else got a cube which was a little tight, the adjustments mentioned below may be appliable.
1. First open the center piece of six faces, turn each face 90°, then turn the cube & feel if it's ok. If you don't like it, repeat.
2. Further adjustments follows one's own habits.
A. Usually Front, Back, Left, Right. Adjust the degree of tightness to the same.
B. Personally, the Bottom should be a little tighter than four faces above. Because the Bottom isn't usually turned. What's more, if the Bottom is too loose, turning would be stuck.
C. As the Top face is usually used, it can be adjusted a little loose, so that it's easily turned to speed up the turning.

Above is my personal conclusion, based on my own experience. I used to buy cubes in local hobby stores, the cubes baught there usually do not have the tightness problem. Cubes from online shopping may do. Your questions are welcomed. I'm just a beginner, so i would be appreciated if you gave me any suggestions or sharing.

While I'm not completely sure, I think that when you buy a cube with screws, the tensions are not equal on all sides. So after you get one, if you tighten or loosen certain sides the same amount, like 90 degrees, the sides may not be the same.

Here's one way to make sure that they're all the same. Remove all of the center caps and tighten each screw as far as it will go. Now that all of the sides are the same, loosen each side the same amount. If you loosen one 180 degrees, do the same to the other sides. Using this approach should make all sides the same. If you want certain sides to be looser or tighter than others, you can do that too.

By the way, that link you posted needs to be removed. Though it doesn't work now (it did yesterday, but not today), in the Forum Rules it states:

"Avoid linking directly to pages of sites selling copies of puzzles that are "protected by their rightful owners"."

When the link worked, it did go to a page selling KOs. Because of that, it needs to be removed.