Formal:
* สวัสดีค่ะ/ครับ (sa-wat-dee khap/kha) ชื่อฉันคือ (cheu chan khue)... This is the most formal way to introduce yourself. "Khap" is used by men and "kha" by women.
* สวัสดีค่ะ/ครับ (sa-wat-dee khap/kha) ชื่อของฉันคือ (cheu khong chan khue)... This is also a formal way to introduce yourself, slightly more polite than the previous option.
Informal:
* สวัสดี (sa-wat-dee) ชื่อฉัน (cheu chan)... This is a casual way to introduce yourself.
* สวัสดี (sa-wat-dee) ผม/ฉันชื่อ (pom/chan cheu)... This is another informal way to introduce yourself. "Pom" is used by men and "chan" by women.
You can replace the "..." with your name. For example, if your name is John, you would say:
* สวัสดีค่ะ/ครับ (sa-wat-dee khap/kha) ชื่อฉันคือ จอห์น (cheu chan khue john).
Remember to use the appropriate gendered ending (khap/kha) based on your gender.