To create TIFFs I would recommend generating a PDF about twice the size of your desired figure, then viewing the PDF in IrfanView and saving as a TIFF so you can produce a high quality image. Note that whey you produce a large figure you will need to vary the marker size, text size, line thickness and tick thickness so the scaled image in Word results in a desirable figure (see code samples below). This is very similar to @JosephWright's method, but saves an image file which is required by some journals separate from the image in the text.
Generate a PDF of your figure with your LaTeX front end, I use a .tex file such as the one here:
\documentclass{article}
\newlength\paperSize
\newlength\figureheight
\newlength\figurewidth
\newlength\markSize
\setlength{\paperSize}{6in}
\usepackage[paperheight=1\paperSize,paperwidth=1.25\paperSize,margin=0in]{geometry}
\usepackage{siunitx}
%for .tikz figures:
\usepackage{pst-all}
\usepackage{pstricks-add}
\usepackage{pgf}
\usepackage{pgfplots}
\pgfplotsset{compat=newest}
\pgfplotsset{plot coordinates/math parser=false}
\usetikzlibrary{plotmarks}
\begin{document}
\setlength\figureheight{0.65\paperSize}
\setlength\figurewidth{0.65\paperSize}
\tikzstyle{every node}=[font=\huge] %vary font size in figure
\setlength\markSize{5pt} %vary marker size
\begin{figure}
\input{sample_figure.tikz}
\end{figure}
\end{document}
The input file looks like this, where variables are automatically included using mat2tikz (Matlab function file to produce .tikz):
\begin{tikzpicture}
\begin{axis}[%
major tick style={draw=black, thick},
width=\figurewidth,
height=\figureheight,
scale only axis,
xmin=0,
xmax=2,
xtick={0,0.5,...,2},
xlabel={x label text},
ymin=0,
ymax=2,
ytick={0,0.5,...,2},
ylabel={y label text},
legend style={at={(1.03,0.5)},anchor=west,draw=black,fill=white,legend cell align=left}
]
\addplot [
color=black,
only marks,
mark=triangle*,
mark options={mark size=1\markSize,solid}
]
table[row sep=crcr]{
0 0.75\\
1.5 1.25\\
};
\addlegendentry{Legend entry 1};
\addplot [
color=black,
only marks,
mark=square*,
mark options={mark size=0.85\markSize,solid}
]
table[row sep=crcr]{
0.25 1.0\\
0.75 1.75\\
};
\addlegendentry{Legend entry 2};
\end{axis}
\end{tikzpicture}
This is what the PDF looks like:

Once you have a PDF of your figure, open with IrfanView and do the following:
- Convert to grayscale (ctrl+G)
- Auto-crop (ctrl+shift+Y)
- Change image resolution to 300 dpi (ctrl+R, 96>300)
- Save as TIFF (S, change "Save as type" to "TIF")
Right-clicking and viewing properties should show 300 dpi instead of 96 dpi.
.eps
figures