What should I order from a Thai Restaurant? ?

Sates (satays) are always good and safe. Other safe things you can order: chicken and pineapple fried rice, pad thai, crab cakes, papaya salad, and fried banana with ice-cream for dessert.

Thai food is wonderful, but can be too spicy. My local restaurant has a chili grading from one to five to help with choices. Pad Thai, as another answerer said, is a noodle dish and not normally spicy. It is rice noodles, bean sprouts, lime juice, tamarind, spices and ground peanuts (with pork, or dried shrimps etc)
Coconut curry is delicious, but check the spice rating.
Ask the waiting staff for help as they will want you to enjoy your food.
Laab is a meat salad.
Massaman curry is a southern Thai curry with meat and potatoes, not too spicy from my experience.
Just jump in and enjoy.
Thai food is traditionally eaten with loads of stuff on the table that everyone digs in to.
Son in law eggs are hard boiled deep fried eggs with a little sauce - my favourite.
Vegetable side dishes will be milder.

pad thai is a rice noodle dish with all sorts of goodies in it. you might want to make sure to ask that they don't make it too spicy if chilli bothers you. otherwise, it's a good Thai staple.

OK ! lol youre too cute for doing it ok...first if you want to admit youve never tried it, tell him then, when you get there. laugh it off and say youve always wanted to try it etc...

Pad Thai with chicken is very basic(pasta, cilantro, lime, peanuts, very yummy and nothing crazy)

Spring rolls are awesome

miso soup is delicious and a very plain broth with tofu, it has no flavor.

there salad is just reg lettuce and veggies they serve it with either a peanut or ginger or miso salad dressing, pick one and ask for it on the side, that way if its ' not to your liking' you can just eat it plain.

Thai chicken is nice :]
have a look at some of foods native to thailand here;
http://allrecipes.com/Recipes/World-Cuisine/Asia/Thailand/Main.aspx

good luck.