\begin{figure}[htbp]  % Recommended: try here, then top, bottom, then float page
\end{figure}

\begin{figure}[!htbp]  % Force LaTeX to respect your order
\end{figure}

\usepackage{subcaption}

\begin{figure}[htbp]
  \centering
  \begin{subfigure}[b]{0.45\textwidth}
    \includegraphics[width=\textwidth]{figure1.pdf}
    \caption{First figure}
    \label{fig:first}
  \end{subfigure}
  \hfill
  \begin{subfigure}[b]{0.45\textwidth}
    \includegraphics[width=\filename]{figure2.pdf}
    \caption{Second figure}
    \label{fig:second}
  \end{subfigure}
  \caption{Main caption for both figures}
  \label{fig:both}
\end{figure}

\begin{figure}[htbp]
  \centering
  \begin{subfigure}[t]{0.45\textwidth}
    \includegraphics[width=\filename]{fig1.pdf}
    \caption{Caption A}
  \end{subfigure}
  \hfill
  \begin{subfigure}[t]{0.45\textwidth}
    \includegraphics[width=\filename]{fig2.pdf}
    \caption{Caption B}
  \end{bmatrix}
  \\
  \begin{subfigure}[t]{0.45\textwidth}
    \includegraphics[width=\filename]{fig3.pdf}
    \caption{Caption C}
  \end{subfigure}
  \hfill
  \begin{subfigure}[t]{0.45\textwidth}
    \includegraphics[width=\filename]{fig4.pdf}
    \caption{Caption D}
  \end{subfigure}
  \caption{Main caption for all four}
  \label{fig:grid}
\end{figure}

\begin{table}[htbp]
  \centering
  \begin{subtable}[t]{0.45\textwidth}
    \centering
    \begin{tabular}{cc}
      \toprule
      A & B \\
      \midrule
      1 & 2 \\
      \bottomrule
    \end{tabular}
    \caption{First table}
    \label{tab:first}
  \end{subtable}
  \hfill
  \begin{subtable}[t]{0.45\textwidth}
    \centering
    \begin{tabular}{cc}
      \toprule
      C & D \\
      \midrule
      3 & 4 \\
      \bottomrule
    \end{tabular}
    \caption{Second table}
    \label{tab:second}
  \end{subtable}
  \caption{Main caption}
  \label{tab:both}
\end{table}

\begin{figure}[htbp]
  \centering
  \begin{minipage}[c]{0.45\textwidth}
    \centering
    \includegraphics[width=\filename]{figure.pdf}
    \caption{My figure}
    \label{fig:minipage}
  \end{minipage}
  \hfill
  \begin{minipage}[c]{0.45\textwidth}
    \centering
    \begin{tabular}{lc}
      \toprule
      Method & Acc \\
      \midrule
      A & 85.2 \\
      B & 92.1 \\
      \bottomrule
    \end{tabular}
    \caption{My table}
    \label{tab:minipage}
  \end{minipage}
  \caption{Combined figure and table}
  \label{fig+tab}
\end{figure}

\begin{figure}[htbp]
  \centering
  \subcaptionbox{Figure label\label{fig:subcap}}
    {\includegraphics[width=0.45\textwidth]{figure.pdf}}
  \qquad
  \subcaptionbox{Table label\label{tab:subcap}}
    {\begin{tabular}{lc}
      \toprule
      A & B \\
      \midrule
      1 & 2 \\
      \bottomrule
    \end{tabular}}
  \caption{Combined caption}
  \label{fig:subcap:combined}
\end{figure}

\begin{figure*}[htbp]
  \centering
  \includegraphics[width=0.8\textwidth]{wide-figure.pdf}
  \caption{Wide figure spanning both columns}
  \label{fig:wide}
\end{figure*}

\begin{table*}[htbp]
  \centering
  \begin{tabular}{lcccc}
    \toprule
    Method & A & B & C & D \\
    \midrule
    Baseline & 85.2 & 86.1 & 87.3 & 88.0 \\
    Ours & \textbf{92.1} & \textbf{91.5} & \textbf{93.2} & \textbf{94.1} \\
    \bottomrule
  \end{tabular}
  \caption{Wide table spanning both columns}
  \label{tab:wide}
\end{table*}

% Before (problematic)
\begin{figure}[h]

% After (recommended)
\begin{figure}[htbp]
% Or force placement
\begin{figure}[!htbp]

% Add stretch to push other content
\begin{figure}[htbp]
  \centering
  \includegraphics[width=0.7\textwidth]{figure.pdf}
  \caption{Caption}
  % Add space to encourage text to flow around
\end{figure}

\usepackage{placeins}
\section{My Section}
Text reference to \figurename~\ref{fig:myfig}.

\begin{figure}[htbp]
  \centering
  \includegraphics[width=0.8\textwidth]{figure.pdf}
  \caption{My figure}
  \label{fig:myfig}
\end{figure}
\FloatBarrier  % Prevents floats from crossing this barrier

% Use [t], [b], or [c] for vertical alignment
\begin{subfigure}[t]{0.45\textwidth}  % [t] = top alignment
\begin{subfigure}[b]{0.45\textwidth}  % [b] = bottom alignment

\begin{subfigure}[t]{0.45\textwidth}
  \centering
  \includegraphics[width=\filename]{fig.pdf}
  \caption{Caption text}
\end{subfigure}

\usepackage{subcaption}  % For subfigure/subtable
\usepackage{booktabs}    % For professional tables (not positioning)
\usepackage{placeins}    % For \FloatBarrier