Notation for the ith row and column of a matrix

When noting the $i^{th}$ scalar of a vector $\mathbf{x}$ one usually does it as $x_i$, since it is a scalar

When doing this for matrices that are being denoted in bold, let's say $\mathbf{A}$, how should I write the $i^{th}$ row or $j^{th}$ column?

This question provides some insight as to how to distinguish from rows and columns but does not address any possible standards for doing it as $\mathbf{A}_{i*}$, $A_{i*}$ or maybe even $\mathbf{a}_{i*}$

Is there a preferable form?

There is no standard notation. Depending on the assumed lectureship you could use ${\rm row}_i( A)$ or $ A_{\,i\,\cdot}$ for the row matrix $[a_{i1}\>a_{i2}\>\ldots \>a_{in}]$, and ${\rm col}_j( A)$ or $ A_{\,\cdot j}$ for the column matrix $$\left[\matrix{a_{1j}\cr a_{2j}\cr\vdots\cr a_{nj}\cr}\right]\ .$$ You then would have, e.g., $${\rm elm}_{ij}(AB)={\rm row}_i(A)\cdot{\rm col}_j(B)\ .$$

The notation I've usually seen for the $j^{\text{th}}$ column of a matrix $\mathbf{A}$ is to call it a column vector $\mathbf{a}_j$, just attaching the number of the column to the lowercase version of the letter used to denote the matrix. I don't know that I've seen a similar notation for the rows of a matrix, but $\mathbf{a}_{i*}$ seems like it would be the most consistent.