LaTeX works on many computer platforms so
file names deserve some thought.
Safest is to name your graphics simply, in particular without spaces.
For example, if you want to organize your files by keeping all
graphics in a subdirectory, then something like
\includegraphics[width=30pt]{pix/mom.png}
is portable and future-proof.
Spaces in file names are traditionally somewhat problematic, but are now generally supported. However, if you have spaces in the name, and you have issues, you may wish to try removing the spaces as the first step.
Accented character support is somewhat variable; there are issues with some systems, particularly on Windows. If you find issues with accented characters in file names, try using only ASCII characters for a test.
A common way to lay out source files is to put all graphics into a subdirectory.
You can then include the relative path, as is shown above; notice that the
/ character is used to separate parts of the path even on Windows.
If you have a lot of graphics, you might want to set up the subdirectory
in advance. That can be done using \graphicspath, which needs a braced entry
for each subdirectory. For example, to include both figs and pics
subdirectories, we would have:
\graphicspath{{figs/}{pics/}}
Notice in particular the trailing / in these.
As discussed, LaTeX easily uses graphics from most sources, including plots from scientific software. When you do that, you probably want to save as a PDF if you can, as this is a scalable format. If you do need to create a bitmap, aim for high resolution. You can make mouse-created graphics that include LaTeX snippets with Inkscape. An alternative that in addition extends those drawing techniques to three dimensions is Asymptote. These two produce their output as files that you include in your document.
You can also create graphics such as drawings that are especially suited to LaTeX, with very high precision as well as equations and labels that match your document. You can draw graphics directly inside your document, which is convenient although at the cost of more complex documents with larger requirements, by using TikZ. An alternative is PSTricks.
LaTeX’s float placement is complex.
The most common request is to have the figure placed
in the output exactly where it lies in the input.
The float package will do that.
\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage{graphicx}
\usepackage{lipsum} % dummy text for filler
\usepackage{float}
\begin{document}
\lipsum[1-7]
\begin{figure}[H]
\centering
\includegraphics[width=0.5\textwidth]{example-image}
\caption{An example image}
\end{figure}
\lipsum[8-15]
\end{document}
Note the H option, which puts the figure ‘absolutely Here’.
However it is often not recommended to use H, because it may
create large portions of white space in your document.
We will see soon that we can put tables in floats; they will go
into a table environment. However, we don’t have to put graphics in the
figure environment or tables in the table environment; this is just
convention.
You might want to have other types of floating environment; each type is
inserted independently. You can do that using the
trivfloat package. This provides a single
command, \trivfloat, to make new types of float.
\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage{graphicx}
\usepackage{lipsum} % dummy text for filler
\usepackage{trivfloat}
\trivfloat{image}
\begin{document}
\begin{image}
\centering
\includegraphics[width=0.5\textwidth]{example-image}
\caption{An example image}
\end{image}
\end{document}