The tips I would give you:
1) Keep Darkside up 100% of the time if possible. It's a direct dps increase and gives you access to a bunch of other abilities.
2) Don't be afraid to spam Unleash, especially if you need AOE enmity generation. Holding aggro gets easier and easier as you level DRK up, and enmity generation is one of DRK's strong points.
3) Syphon Strike and Blood Price are going to be your main tools for regaining MP, use them as often as you can.
4) I would actually put all your points into VIT starting out, as you will need to learn to tank and it gives you more room for error at the start. Once you hit 50 or 60, you can swap your points to STR if you feel comfortable doing so. You will eventually want all of your points into STR, but there's no hurry while you are still learning.
I won't go in to too much detail here, just some basic tips to get you started
