Overall, it's quite disjointed and noisy.
All those textures and noise filters make it hard to read the actual features of the map like the rivers or many of the labels. Try to maintain as much visual contrast for actual information as you can rather than spending it on decoration. Try to keep decoration where it's not going to obscure or be mistaken for content.
Using every font you have installed is also a bad idea. You should try to pick fonts from a single family, or at least which look similar enough to pass for a family. Clear, legible fonts are also important, particularly for labels. Make sure to read "Positioning Names on Maps" by Eduard Imhof for an excellent introduction to labelling. Labelling maps is one of the most difficult parts of good cartography and one of the things that sets a good cartographer apart.
Have a clear idea of what the map's purpose is. What should and shouldn't be included and how it should be presented depends on what the map is for. Think about who is making the map, who the map is for, how good the information the map is based on is, the sophistication of geography and navigation, the scale and extent, and the tools and media available for producing the map. Look at real maps that have similar purpose and context (For a marine chart of a large enclosed sea in a fantasy setting with approximately 14th century European level navigation, try looking for a real life 14th century chart of the Mediterranean.)
You have a whole lot of river bifurcations. Rivers join together as they flow downhill. Places where rivers split are unstable and can be very short lived, they are also almost always very short as the branches join up a a short way on. There are only a very small number of large, non-seasonal, naturally occurring river bifurcations, and they don't generally look like a regular confluence drawn backward. While you're starting out, it's safest to stick to the rule "rivers join but never split" and then learn to work in the specific exceptions. Lakes should be considered wide sections of river.
You also need to consider what a river says about the elevation of the land around it. If a river starts near a coast and flows across the landmass to the other side then remember that the drop down to the nearby coast from where the river starts needs to be the same as the drop along the entire length of the river going the other way.
You also have a river with no outlet. There are rivers that do this like the Okavango, bit this is unusual and requires specific conditions. Lakes with no outlet (Endorheic lakes) are a bit more common, but still require special conditions, and they will be very salty (The Dead Sea, Caspian Sea, Great Salt Lake, and what's left of the Aral Sea are examples.
If you have a big map, you're probably better off to scale it down rather than chopping it up. Or do both so there's and overview if you really have fine details that would be lost. This map really doesn't need to be that big.