Hey! Nice mini to start with. Good colour scheme
1. Practice!
2. Good minis have plenty of contrast to make detail stand out. For example, the runes on the hammer could have some (more) black wash around them, though don't go overboard. Then the edges on the weapon should be highlighted with a bright silver. Start with darker paints and work up, generally. The chainmail could do with a black wash, especially across the shoulders, then a gentle drybrush to highlight.
3. Plenty of thin layers, without too much change in colour between them. this is the way to do good skin tones, certainly for important models. For large armies you may want a quick method.
4. There are loads of articles on this site by amazing painters. They are well organised - look at some of the ones for beginners.
5. Don't be disheartened if things take a while. There have been times I have put things up and not gotten a great score !!