Let me just start by saying that eating out can be very tough! You don't always know how your food is being prepared. It seems like 90% of the options come with some sort of bread/tortilla/french fry, etc. Sauces are almost always thickened with flour or corn starch. One of my favorite ways to keep things in check is to sub OUT items on the menu for more veggies or other healthier options!! While this isn't always possible, you never know if you don't ask!
Top 5 restaurant substitutions I have managed to get- just by asking!
1) Veggies instead of Tortilla Chips at a Mexican restaurant (Changarro in West Chicago did this- see picture!) This was one I never thought I'd get, but I just asked if there was something else besides chips to dip in the delicious salsa (like veggies), and this is what they brought me!
2) Veggies instead of fries (very common- occasionally there will be a small up charge, but well worth it!)
3) A Stir Fry with extra vegetables instead of rice or noodles
4) A lettuce wrap or bed of greens instead of a bun or bread. This could be with a burger, chicken, fish, heck I've even eaten an "italian beef salad"
5) Oil and Vinegar instead of other salad dressing. This one I recommend because salad dressings are notorious for having all sorts of weird added ingredients and sugar. My best bet if I'm eating out is always Oil and Vinegar, because at least that way I have a better idea of what I'm eating. Sometimes if there are enough delicious ingredients in the salad, I just leave off the dressing all together.
If you are being very strict or have food allergies, you can ask your waiter about what types of oils they use for cooking and where the meat/produce came from. Depending on the restaurant, they may or may not know the answers to those questions. If there is an option of cooking oil, my top choice would be coconut oil, or a form of animal fat (butter, lard, duckfat, etc- since they have more saturated fats, and can go to high temperatures better). I would stay away from highly processed cooking oils like vegetable oil, canola oil, etc. Here is a guide for which fats to cook with, which to eat raw, and which to avoid all together! Since I don't go out to eat very often, I typically just try to do the best I can, knowing that it is a treat and I can't control everything about the way my food is prepared all the time.