Assuming you have not done this before, here is how to accomplish a good safe tow. Using the appropriate sized tug for the task at hand, line up on the field facing into the wind. Stretch out the towline downwind. Out of courtesy for other pilots using the active runway, always have the loop installed into the nose of your glider before going out to the start point.
If you are sharing the field with other flyers, power or sailplane, this means tying up the flight line for a minimum amount of time. And of course, safety; exposing your body to flight traffic for a short a time as possible. Hook up your sailplane to the towline. Check your controls. Take slack out of line with the tug. Make sure your ailerons and rudder are not coupled on the sailplane.
If you are not using a retract, a tow off the grass with out a Dolly should be no problem. The friction of the fuse on the turf will make it relatively easy to get going by holding a little down aileron on the high wing. If you are using a retract, the tug pilot should take care to ease on the throttle until things get moving. Once the slack is out of the line, the tow pilot can gently apply full throttle and go. Level your wings and let the sailplane rise on its own accord, if it doesn't, gently input up elevator to get things going.
The tow pilot should establish a very gentle turn as soon as things are up and going about 75 feet or so. It is important to not fly straight out too far before turning as the first turn with the sailplane is difficult to see when it goes knife edge relative to your eye. The glider does not turn with the tug but remains straight and level flight, UNLESS you get out of position, then you must correct or release and try again. Keeping the wings level keeps the tow line tight in the turns.
SET YOUR TRIMS NOW for a reasonable climb, once you get to higher altitudes it will be difficult to do this. The tow pilot must judge his rate of climb based on the glider he is towing; the glider pilot, who can see the flag and if there is any slack, can direct the tow pilot to climb or level out as the case may be.
After a few tows you will develop your own rapport between tug and sailplane pilot. When in doubt release. No if, ands, or buts. You can always do another tow. Do not fly higher than you can see. This sounds obvious, but beginners forget that they have a release switch in their hand, and blame the tug pilot for towing him too high. Watch the flag (if you use one), it will tell you if there is slack in the line and also when you are released.
The tug pilot should fly large gentle circles or figure eights. The climb rate should be in accordance with the power of the tug and weight of the glider. Shallow is usually better than too steep. If the glider overtakes the tug, then the tow pilot needs to increase his angle of attack or the glider pilot should feed in a little up trim. Spoilers should not be used as this just creates more drag.
The direction of at least the first turn should be established before taking off. The sailplane pilot's job is to keep his wings level using ailerons only. Once released you can re-couple ailerons and rudder if you like. Keep in mind some high performance scale sailplanes cannot be flown coupled. Learn now, and save yourself the trouble later.
The concept that seems the least understood in towing is that the speed of the tow is determined by the angle of attack of the tow plane, NOT the throttle setting. Use full throttle, and if you are flying too fast for the sailplane just climb more steeply and convert speed into altitude. If you start playing with the throttle during a tow you will often create slack in the line.
These are the basics. Please allow that there are many variations on this technique. Nothing is cast in stone, but by and large this system works and is proven to work. Be advised that while towing from the tail of the tug is possible, it is not safe. NEVER tow from an attachment point underneath the tug!