To do something yourself is to take personal responsibility as opposed to leaving it with a third party. To do something by yourself is to do it alone, without the input or assistance of any companions. Sometimes they are interchangeable, but sometimes they are distinct.

Do it to yourself meaning?

: the activity of doing or making something (as in woodworking or home repair) without professional training or assistance broadly : an activity in which one does something oneself or on one's own initiative.

Do you hyphenate do it yourself?

But because it's not, you follow the rule that says you hyphenate these do-it-yourself compounds any time the hyphen aids comprehension. These rules apply only to compounds you assemble yourself. If your term is already in the dictionary, just write it accordingly: good-looking, well-adjusted, man-eater.