You raid as a dps DK, right?
Ok, I'm not going to write a long post here on min/maxing professions. It's been well-established since Lich King was released that Jewelcrafting/Blacksmithing are the way to go for providing the best raid benefits. There's been plenty of posts and blogs covering the topic in detail; if you want more info, let me know and I'll point you in the right direction.
Can you raid effectively with other professions? Sure, you can. They're not quite as good, but you can get by.
For now, however, I'll assume you're like me and are JC/BS. So, two things about raiding with those professions, just as simple reminders.
1. Don't forget to create your three gem sockets: bracers, gloves, belt. I have forgotten a time or two when I got a new piece to make those sockets, and I lost out on the very nice stat bonuses they provide.
2. Distribute your gems carefully. If you armory Hinenuitepo, you'll see I have two +20 hit gems. This gets me to the cap, which is very important. Other than hit/expertise cap issues, you should ignore socket bonuses and gem strength. The only other exception to this is to ensure your meta gem activation; use a Nightmare Tear to fulfill your blue gem requirement, and do so where it will get you a +6 strength socket bonus (legs/chest).
This brings up a related point: DON'T BE CHEAP. There's no reason to skimp on your main. There's no reason to put non-epic gems in your slots or have suboptimal enchants. It's just too easy to make money in the game. Wowenomics and many other sites can give you plenty of ideas, but the simplest tip of all with the two professions above comes from jewelcrafting. Do the daily every day - it takes 10 minutes at the most. You can find all the mobs that drop the quest items nearby in Icecrown or Storm Peaks. People forget that most animals, including the rhinos up in SP drop the northrend ivory. Anyway, you can turn your token into quick cash either by trading the token into a Dragon's Eye or by getting five infinite dust and creating a nightmare tear. I usually make the tear as it is worth more than selling the raw eye and five dusts sold seperately on my server - but check your own server for prices.
Happy Monday, and more to come!
-finish my leveling guide, and more