In Muay Thai fighting is much different than sparring. The main purpose of sparring is to learn new techniques and combinations while the main goal of fighting is simply to win by all possible means. Even the full power sparring will not completely emulate a real Muay Thai competition fight. When you fight for real, you hold nothing back and you don't bother with some possible injuries that may happen in the process - this is the ultimate price of winning after all.
That said, it doesn't mean that you don't have to protect yourself and conserve your energy.
You need to have a game plan and push yourself to the highest level of your skills. Five 3 minute rounds, 15 minutes of a maximum physical and mental performance. A quarter of an hour of your lifetime and a few bruises is not a very big price to pay for a great achievement that will last a lifetime. And I'm not talking even about a great fame and recognition - although it is totally possible if you are really good and win a high level Muay Thai competition - but about a feeling of pride that comes from one's achievement. And stepping into the ring to give everything is a great achievement, no matter what is the outcome of the fight.
Effective Muay Thai fighting tips. I hope you will find them useful:
pace yourself, conserve your strength for 5 long rounds unless you're the type of the fighter that goes for a quick knockout in the first round. And God have mercy on your soul if you don't get KO in the first round. Recently that's what happened to Ronda Rousey in her fight with Holly Holms.
Don't let your opponent get away with his strikes unpunished: this on is very important. Don't let your opponent to control the tempo of the fight. Counter-attack after his every successful combination.
in Muay Thai fighting is not only about a physical or technical advantage: confidence and mental strength are as important as a physical fitness.
try not to show any pain or a weakness after receiving a devastating attack. I know it may be hard but it will greatly discourage your opponent. The more you train and condition your body the less pain you will feel when getting tagged.
and remember that your opponent is probably as tired as you are right now and he needs a rest as much as you do. Fighting is, ultimately, a clash of wills and if you are able to push yourself when you feel that you've got nothing more left - you will win.
Learn about your opponent at first - spot his weakness and defense gaps. Estimate his speed and his timing. Target his weak spots and attack with full power. Put a knockout power in every punch and kick you deliver, even if they get blocked you will send an important message.
Train hard. And then some more. And then even a little bit more - the more you train and spar the more confident you become. This will show in the ring.