Taping a baseball bat can make the bat thicker and easier to grip for the hitter. How you tape the bat is really up to the preference of the hitter. Just make sure you hold the tape taught as you tape so there are no bubbles or ridges in the taping.
Decide which method you want to use to tape your bat. You can use a criss-cross pattern, which leaves some wood exposed and forms a diamond pattern, or you can do a full wrap, which covers the whole handle and can make the handle feel thicker. You can also form a rope with the tape and wrap the rope up the handle, or you can combine a full wrap with a rope. You can either build up the knob and make it thicker or leave it bare. Once you decide how you want your bat taped, you can concentrate on technique.
To tape with a criss-cross pattern, start at the base of the handle and begin twisting the tape up the handle like a candy cane. Tear the tape when it is about 12 inches up the handle. Start again at the base and twist up the other direction to form a diamond pattern in between the tape. Take your time starting the second strip to get the angle the same as the first strip. Use two short strips to tape once around the base and at the top of the handle, so the long strips don't peel off.
For a full wrap, start at the base and continually wrap the tape around the handle, overlapping about 1/4 inch each circle. Tape 8 to 12 inches up the handle.
To form a rope up the handle, tear off a long strip and roll it into the rope. Use a small strip to tape one end of the rope to the base. Wrap the rope diagonally up the handle, about 8 to 12 inches. Tape the top of the rope with another small strip.
You can also use a full wrap, then put a rope on top. This will build up your handle quite a bit so it will feel much thicker.