Summarize:

Practicing with another person is very different from developing your technique on your own or working on a punching bag. While many students may feel intimidated, though, it's important to remain calm and relaxed. The best way to prepare for a one-on-one sparring match is to focus on the basic moves and remember to keep up your guard against a counter-strike.  The best times to hit an opponent are when they're punching at you, when they're not expecting it (by changing up your rhythm, for example), or when you're at an angle that would be difficult for your opponent to block.  Remember to use your non-dominant hand to deliver a short, sharp jab. This sets up the bigger punch with your dominant hand, and it can also confuse or intimidate your opponent. Don't emphasize speed, as a fast punch often lacks the body strength behind it that a slower punch can deliver. Work on your form and on delivering the best, most powerful hits you can. There are many techniques within Muay Thai, and mastering them all would take many years. However, even as a beginner you may be able to incorporate some traditional techniques into your training, which you can then develop and build off of.  Kao Dode (Jumping knee strike) - jump up on one leg, then use that leg's knee to strike your opponent with a direct knee hit. Kao Loi (Jumping/Flying knee strike) - take a step forward, begin jumping off of one leg as though you were going to use the knee or foot of that leg, then switch in mid-air to deliver a knee strike with the other leg. Kao Tone (Straight knee strike) - hit with the knee straight and upward, ideally in close proximity to your opponent. Kao Noi (Small knee strike) - when you're grappling with an opponent in close combat, use your knee to strike the upper thigh (but not the groin) of your opponent to wear him or her down. It can also be used to block a kick or knee strike from your opponent. In a real combat situation, you'll need to move fast and incorporate a lot of different moves very rapidly. Strength and form should come before speed, but as you advance you can work on becoming a more proficient fighter with faster response times. You should also think of your opponent as a walnut protected by a hard shell. You have to crack through the outside shell (with hits to your opponent's lets and arms) before you can get to the nut (which in this metaphor would mean a direct, close-proximity hit to the head or abdomen).  Dodging a hit and counterattacking your opponent works well at the beginning of a match, but it can quickly tire you out. As you progress through the match, you'll want to spend less time moving around and focus your energy on blocking direct strikes from your opponent, then finding an opening in your opponent's stance. Keep moving forward as you spar with your opponent. This puts him or her on the defensive, which can also give you more momentum as you prepare to land a direct hit. Training on your own is a good start, and sparring with a friend or other workout partner is a good next step. If you're serious about becoming skilled in Muay Thai, though, you may want to work with a trainer who has an extensive background in martial arts. A trainer can help you find your own weaknesses/vulnerabilities, perfect your technique, and take your training to the next level.  You can find Muay Thai trainers and gyms in your area by searching online or by checking a local phone book. Remember that becoming proficient in Muay Thai takes time, just like any other learned skill. Be patient, and if you decide to work with a trainer, follow his/her training advice on how to improve your stance, technique, and form.
Learn how to spar with an opponent. Practice some Muay Thai techniques. Combine the various moves to wear down an opponent. Consider working with a professional.