People can be mean, but they do have good intentions. On the issue of blood: it's rarely plain red, specially if it's on the body; and it has a very high specularity, meaning highlights will be very white and very small. Check these to see what i mean:
Your biggest problems have nothing to do with the digital part of digital painting. So about the only thing you could do, apart from improving your drawing and lighting skills, is use bigger brushes so that everything doesn't look scribbly and textured.
Find where your darkest darks and your whitest whites are going to be and then work in between those. Some of your darks don't feel dark enough, like around the face, skin and parts of the jacket. It's also important to note that shadows aren't just black, they're all kinds of colors. Normally if you want to paint something that has a warm light, you want cool shadows. Another possible trick is to use the complimentary color to create the shadows. You might want to try doing greyscale studies of objects and people to help you better understand how to create volume, depth, and value. That should help quite a bit.
I also might suggest using a hard or soft round brush with opacity (The fifth and sixth brushes on the list). They might help you get smoother blends.
I would start by studying the techniques of Andrew Loomis, especially his technique on drawing faces. It's simple, but freakishly helpful when it comes to facial structure and proportion. His book, Drawing the Head and Hands, is available as a pdf online. His other books are also online, but I haven't read them yet.
For an excellent introduction, check out Stan Prokopenko's videos on youtube: [link] They may be all you need, but I encourage you to read the Loomis book, too.
Humans have been the one thing I haven't been able to draw since I began to take art seriously(ish). This year, I discovered these resources and although I'm by no means a master, the level of improvement brought on by studying Loomis' technique is noteworthy. If I can do it, anyone can do it. And you're off to a good start; with a bit more practice, you'll be perfectly fine!
Oh! Sorry. Well in that case, here's a few more (hopefully) helpful tutorials:
Skin: [link] <-- I noticed in your painting that you used to little a range of colors on your subject's skin, which made it look a bit flat. Like this tutorial suggests, I'd use more warm, reddish tones to give it life. And here's part two of that tutorial, on skin tones (super helpful): [link]
If you aren't concerned with anatomy my tip would be to practice coloring black and white photos. It helps with understanding lighting. You can apply that knowledge to your digital paintings. practice coloring shapes like cubes, spheres and cones, as well. Study color theory.
It looks like learning anatomy joint by joint would help. It don't look that bad but the face shows me you are drawing line towards angles that the mouth and not towards the chin, and some proportions are off. It is possible some of the proportions come from the cartoon a Nightmare Before Christmas.