The best way I know of is to string together a few randomly chosen words, and separate them with a digit or special character. In the box below are several passwords; you can pick one or choose others.
These passwords are generated fresh, in your browser, on each page visit; they are designed so that no one besides you knows the passwords you are looking at, not even this website.
You can always make a password shorter and simpler by dropping the last word or two.
It is also important to have different passwords for different sites. I use a password manager to keep track of passwords, and you want to have your passwords stored encrypted in a password manager.
One free password manager is KeePass.
Note: Some sites have restrictions, saying that your password cannot exceed a certain length, or that special characters are not allowed. If you try to use one of these passwords and run aground on a website's rules for passwords, just cut the password down to size so that it fits the site's rules.
THESE PASSWORDS AND ANY OTHER SOFTWARE AND ADVICE ARE PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THESE PASSWORDS AND ANY OTHER SOFTWARE AND ADVICE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.