Here is what I did, because throwing straight was one of my objectives. Keep in mind, Disc Golf is still mostly unheard of in Myrtle Beach, so it was just me, myself, and this website. I know you said "What's the use of going to a field if I don't know the right technique?"
Well, here is what I did. I went out to a field, and just started tweaking myself. I would empty my bag, and focus on what worked. It's two fold
1. You will learn what your discs will do. There is a key to that, and that is use the discs that are designed to fly close to that line of stability. I love the Flick, but that disc is a Hard disc to throw straight. So I keep that for Doglegs, and other things. A leopard is a great disc to throw to achieve that straight path.
So Key 1: Learn how each disc you own flies.
2. Snap: The snap is what will add more spin. The more spin, the longer the disc will fly, as well as keeping it to a straighter line. *Keep in mind, different discs do different trajectories. So work with the discs that will work the straight line. (i.e. Teebird)
3. You want to aim low. When you are working on this, you will spend time learning what is to low, what is to high. My rule of thumb is to keep the disc out in front of me, but lower than the shoulder. You should be able to see the print on the top of your disc. When you throw, you will want to throw down at an angle "High to low". You'll know if you are aiming to low. (Worm burner anyone?
) Just keep at it until you achieve that right spot.
So, Keep that in mind and go out to a field and just start the tweaking process. ...and yes, it is a process. You won't go from 150ft, to 350ft overnight. I suggest work on one thing at a time.
Start with Grip Read this article, it helped me tremendously. Then work on approach, then work on your throw, etc...
Finally: Setup markers, and aim for them. I suggest 100ft 200ft & 300ft. How can you reach a goal, if you don't know what you are aiming for. so look at that 200ft marker, and aim for it. As if it were a basket. You need a target, and you need to aim for it. Did you ever notice you throw better on a course, than in a empty field. Why? Because you are aiming for the basket. So when you are in a field, you need to aim for something. That'll help you right off the top.
Once you've mastered these little things, then comeback and ask us questions. But you'll find that a lot of it is just figuring it out, and you do that by throwing trial and error. Once you hit that drive, and hit it perfectly, you'll know.
Oh last thing. Drive with your putters and mids for awhile. Trust me, it worketh! It may not sound as cool as driving with a Wraith or... well, in your case, the Groove.
But it will be rewarding to your game. I have two driving putters, and I use them quite frequently! I can throw them straight down the pipe. The majority of what I learned, I figured out on my own. If you can play with a better player, ask them for some tips.
So there you have it, now go out to your field and practice. FYI: Everyone has their own style, so when you ask any of us about a technique you could get 4 different answers. Use what works for you.