You can easily do that with the enumerate
package:
\documentclass{article}
\usepackage{enumerate}
\begin{document}
\begin{enumerate}[{$\bullet$} a.]
\item One
\item Two
\end{enumerate}
\begin{enumerate}[{$\bullet$} 1]
\item One
\item Two
\end{enumerate}
To see more examples just type texdoc enumerate
on your command prompt to get access to the package documentation.
Edit:
As per the comments below, if you want to change the bullet symbol within the enumerate environment you can use this code:
\documentclass{article}
\usepackage{enumerate}
\usepackage{amssymb}
\usepackage{pifont}
\newcommand{\mynewitem}[1][]{\refstepcounter{enumi}\item[#1~\theenumi.]}
\begin{document}
\begin{enumerate}[{$\bullet$} a.]
\mynewitem[\checkmark] Right
\item normal item
\item another normal item
\mynewitem[\checkmark] Right
\mynewitem empty item
\mynewitem[\ding{55}] Wrong!
\item etc.
\end{enumerate}
\end{document}
Note that \mynewitem
accepts every symbol, and the packages amssymb
and pifont
are just to get the \checkmark
and crossed (\ding{55}
) symbols.

\documentclass
\begin{document}
etc. to make it easier for us to help you?