Kengee, when I first started with the tail draggers, before I soloed, I had the same problem you are experiecing. Here is what I learned.

1 Throttle management is the single most important thing in a straight down the center line take off. You have to get the rudder flying and controlling the direction of the plane before applying full throttle. Our field has a 500 ft paved runway and the entrance from the flight line to the runway is at about 40% of the length from the start on the left. I really prefer take offs and landings when the wind is from the right as it give me a longer take off roll and if I touch down near the circle, I have a longer way to overshoot and still not get into trouble. I roll out to the center line and as I'm making my turn to line up, I start very slowly incerasing throttle. All the while, I am keeping full up elevator to keep the tailwheel down. As the plane picks up speed, I keep slowly increasing power. After about 50 to 75 feet of acceleration, I release the up elevator and keep adding power About this point, the rudder has control and I'm at about 50% throttle. From here you can more rapidally add power without verring to the left. However if you jam full throttle at this point you may make a left turn in the process.

2. setting up your plane is important. The tail wheel needs a stiff, but not necessarly a ridigid coupling to the rudder. I use a lot of the sullivan tail wheels and I use the smaller, stiffer spring. I also use the 60+ size one as the tail wheel wire is stoutter and it holds the plane on corse better. The 40 size one tends to fold to one side or the other under full up elevator on takeoff. Go to a paved and smooth area and with the radio on and controlls in netural, push the plane into the wind and watch how it rolls after releasing it. It should roll straight on the course you pushed it. If it is rolling off to one side, bend the tail wheel axel to straighten out this roll. It is important to do this with the radio on and after the plane has been trimmed out so you are not adjusting the wheel to a rudder that is not centered for flight.

3. make sure your engine has the right thrust , IE zero or a bit of right thrust depending on the design of the plane. Follow the plans here. If the plane is built to plan and the motor is mounted straight to the firewall, this is the last area you will tweek to try to fix your takeoffs.

4. Some birds just don't handle well on the ground. The short length compaired to wing span lends its self to bad ground handling, IE the Cubs are know for bad ground handling, both the models and full size I have been told.

5. If all else fails get a gyro and put it on the rudder. I did this for a couple weeks while I was still on the buddy box and it helped the takeoff considerably. I found it was effecting some other things, so I pulled it. I had a cheep one that didn't allow me to control the gain from the radio and had to make adjustment on the ground. If you go this route, get one that you can shut down the gain after takeoff and turn it back on for landing.

Practice, practice, and more practice is the key. Touch and go landings don't count, land, taxi back the pits and do a U turn and take off again. Until you get the hang of it, 10 to 15 takes offs and landings a day is a good goal. More if you can get the runway tiine and have the time.

Don