The best first step Tom could take to solve the equation \(3x - 5 = 26\) is to add 5 to both sides of the equation. This will help isolate the term with \(x\) on one side.
So, the step would be:
\[ 3x - 5 + 5 = 26 + 5 \]
Which simplifies to:
\[ 3x = 31 \]
After this step, he can proceed to solve for \(x\) by dividing both sides by 3.