Sadly I don't have much time, so I'll get around to reading your stories later, but I'm always willing to help someone be evil.
The first thing you should know about being evil is that it means you aren't just a psychopath. It helps, but your psychotic escapades should be directed at some purpose. The fundamental part of being evil is the willingness to do pretty much anything to further your (selfish) purpose. The only thing that really separates it from violent extremists is that your purpose, being evil, furthers your own ends first and foremost, while violent extremists are- at least in their own perspective- furthering an outside cause.
So, what is your purpose?
I'm going to say "revenge" just from context hints and your sig. Best guess also says revenge against the Bretonian lawdogs, or some group of which they are a subset. So, the twisted and vile deeds you do should further your revenge against them. The purpose of revenge being to feel better about something that happened to you, "recreational" havoc is what you're going for here. Identify the people you feel are responsible, and make them suffer. Whether directly or by proxy is your choice, but the idea is to enjoy their torment. This means that any evil you do should be enjoyable (if you find an act distasteful, you'll pass it up in lieu of another way to make your targets suffer even if it doesn't hurt them as much), make an impact on your target (or at least carry with it the potential of such), and have a way for you to either witness or otherwise glean whether or not they are, in fact, suffering from your deeds. That last bit doesn't have to go for every single vile act, but if you can't tell if they care then you aren't doing your job right.
Another thing to consider while trying to make your evil deeper and more real is this- good deeds are not above you. Spending a day volunteering at your local homeless shelter is definitely worth it if it pains your target. The suffering or grace of outsiders is only relevant as it applies to your purpose. If it doesn't matter in any significant way, then just act based on other character traits. If aforementioned homeless shelter means nothing one way or another to your target (and for the sake of argument you have to interact with it), if you enjoy seeing the patterns people's lifeblood make when you gut them, then channel Sarah Rain and have a merry old time. If, however, you are the type to keep your quarrel between you and your prey, then leave them be, interacting in the least obstructive way possible.
Next point is that of survival, and its weight in your actions.
If you can throw your life away to do moderate damage to your target now, or you can run away to plague them for the rest of your life, you run away. If your character is affected by things like "honor" then this equation gets a good deal more complicated (note, however, that concepts like honor are not lost on the wicked: there can be people as upright and honorable as any other even while being otherwise evil). The only time there should ever be a question about running away to continue your deeds is when you can complete something so utterly destructive that it would bring your target to their knees, even if it takes you with them. In your case, this might manifest as an opportunity to distract the BAF long enough that the KNF can achieve decisive victory and crush them into the ground- but by staying long enough to ensure the BAF lose, you give up your chance to make it out alive. That is a dilemma, that should be met with a deep look at yourself. Is your purpose more important than your life? In the case of revenge, I would say that as a rule of thumb, vengeance for someone else's grievance (such as the murder of a loved one) tends to be held more dearly than life, while vengeance for a personal grievance almost never is treated that way. If a person made your life a living hell, and now you get your kicks by hurting them for it, dying to make them pay for it accomplishes nothing for you- rather the opposite, it basically means they won. Basically, how selfish are the motivations for your purpose?
The biggest thing to remember is that being evil is a part of your character, not the entirety of it. Evil does not exist in a vacuum- your character has a history, a way of doing things, and a personality. Evil describes the pattern of their actions, but is not all there is to them.
Hope that helps.
Oh, and to those wondering, expect me fully back (for good, this time) in about two weeks. Mm, what does it say about me that the first post I make in ~two months is a guide on being evil? Ah well. See y'all soon.