My advice is to think about the map before you start drawing:

What is the map for? Each map has a purpose, and good maps are designed to fulfil their particular purpose be it navigation (which is going to depend on the kind of navigation), displaying thematic data (like a weather map), or reference (like an atlas)

Who is making the map? If you are trying to make a fictional map, is the map itself meant to represent an artefact of that fictional world? If it is then someone made it and you need to consider their particular technical knowledge of navigation and cartography, the information available to them and how it was gathered, and the tools available to them for map making. If you toss filters and textures, and map symbols around willy nilly without thinking them through logically, you'll end up with a very obviously computer generated map. If the map is meant to evoke medieval level technology (medieval Europe really didn't do much cartography) but looks like it was produced using modern surveying or remote sensing data, it will look anachronistic.

What shape is your world and where is your map on it? This is really important and if you get this wrong you can end up with a map that doesn't make sense. It's entirely possible to put together a map that only work if the world is simultaneously flat, spherical, and doughnut shaped. This becomes more important if you want to include elements that suggest certain kinds of precision, particularly those associated with navigation like graticules (grids), linear scales, and compass roses. It also gets more difficult as you deal with larger portions of the world (in geography jargon is called "small scale" as the features of the map are drawn small, while "large scale" draws them larger. It's how big things in the map are, not how big the area covered by the map is, that's "extent" not "scale")

Some other advice:

Be wary of just copying elements of other maps without understanding them. Something you see on one real life map may not make sense on your map. Copying an alphanumeric locator grid from a modern road map onto a high fantasy map will just look wrong. There's also a bit of a tendency among fantasy artists to copy each other's bad habits, or to copy really prominent maps to the point it becomes a bad habit (See Left Justified Fantasy Map. Be warned that's a link to TV Tropes and TV Tropes Will Ruin Your Life.)

Don't be afraid of empty space. Don't try to fill frame of your map neatly with features (rectangularitis) and try to avoid swamping all the important details of your map with decorations, patterns, and filters. Sometimes fitting your features neatly into a map can make sense if the world was designed that way, or if the map is highly stylized like a medieval "mappa mundi"

Detail and contrast are finite resources so spend them wisely. Only include what you need to include and only in as much detail as you need. Maximize contrast between important things so they are visible and recognizable. If your background is in the middle of the colour space, then you only have half the contrast possible as if you had it on the edge. That's why maps usually have light backgrounds, especially if they need to show lots of point and line details. Similarly, noise filters and high contrast textures use up a range of the available contrast leaving less for the content of the map.

Labels are hard. They might seem simple, but they aren't. In my opinion, good labelling is what separates cartographers from geographers, illustrators, graphic designers, or anyone else who happens to be drawing maps. If you want a well labelled map, expect to spend a significant portion of the time and effort behind it just on that.