Is it safe to rely on condition evaluation order in if statements?

Is it bad practice to use the following format when my_var can be None?

if my_var and 'something' in my_var:
    #do something

The issue is that 'something' in my_var will throw a TypeError if my_var is None.

Or should I use:

if my_var:
    if 'something' in my_var:
        #do something

or

try:
    if 'something' in my_var:
        #do something
except TypeError:
    pass

To rephrase the question, which of the above is the best practice in Python (if any)?

Alternatives are welcome!