Sailing model boats is best learned by hands on experience as every pond or lake in the world has unique properties. The lay of the surrounding land (hills, indentations, trees etc.) has a great bearing as to wind characteristics. One therefore learns in what conditions the vessel sails best with at the time of sailing. No two weather hours are ever the same so one is making it up as one goes. The main rule is to keep the wind at about 90° to 45° to the Side of the hull as these angles will drive the ship at it's optimum speed.
There are two ways if turning the vessel onto another course, into the wind and with the wind at the stern. The latter is only used when the wind is too strong to turn into as the vessel will loose ground. Turning into the wind is the most popular method as one is then gaining ground and the vessel turns quicker. The idea is to get a decent bit of speed up before turning into the wind as the weight of the vessel will add much needed momentum to the maneuver.
No sailing vessel will sail directly into the wind and looses momentum when sailing about 18° into the wind. 45° is the safest angle to maintain momentum, however on a personal note, I sail 45° in the direction I want to go, changing course to 90° for about 20 feet prior to swinging the helm hard over to make the turn while winching the jib sail over on the opposite tack while the vessel is going round. In the case of a square rigger, the fore mast yards are turned at the same time as the jibs, soon followed by the main and mizzen yards. The final sail to be trimmed is the mizzen boom or driver. If the first attempt is unsuccessful then have another go until one gets it right, however, leave plenty of room to make a few turns just in case a couple go wrong.
Sailing with the wind pushing from the stern is best done by sailing a few degrees off the wind. It is quite difficult to control the rudder with the wind full astern as the vessel tends to snake from side to side with resulting over steer trying to correct the course.
To save the vessel capsizing in a squall (a lump of fast moving wind) or to bring it to an abrupt halt, simply turn it directly into the wind. In the case of a squall, the only hope is that it doesn't last all that long as it is nigh on impossible to hold the vessel on station as the wind will eventually turn it back into the wind. If the squall doesn't let up, turn the vessel round and run for the nearest bank.
It is always handy to have a large 500 ml hypodermic syringe (the type used for injecting horses or elephants), as water will eventually get into the boat and will need to be bailed out. A foot or so of ¼" soft plastic tube fitted to the syringe will aid in bailing.
One major hint is to fit flags to the top of the masts as they will tell you where the wind is coming from for the model as the wind on one's face is never a good yardstick. Keep an eye on the ripples on the water as this is also a good indication where the wind is coming from. During summer months, the morning is often the calmest, while the wind freshens in the mid afternoon and trails off in the evening. To find the evening wind, watch the ripples on the surface and head for them.
Lastly, try sailing maiden voyages on shallow ponds no more than a couple of feet deep just in case the unthinkable happens and one has to go in after it. | 
