Basic Kashrut in a Restaurant

Sometimes I am forced to eat in pareve restaurants with regular Rabbinate kashrut, not mehadrin. What can be done to raise the level of kashrut, and what is especially important to be particular about? The question is not whether it is permitted to eat at this level of kashrut, but how to avoid prohibitions as much as possible: what is the level of concern regarding bread, which vegetables in a salad should one tithe, is it possible to eat lettuce, and the like. If the rabbi has a detailed guide on the subject, I would be happy to be referred to it.

Shalom u’vrachah 

It is impossible to avoid prohibitions without mehudar supervision. 

In order to minimize prohibitions, every vegetable and fruit must be tithed, and every leafy vegetable is forbidden for use. 

And even after all this, the situation is still very problematic, since any spice may contain insects, and one must be concerned that the oil and the other additives have not been tithed. There are also many substances used in industrial cooking that you will not know are being used, and consequently you will not know what problems they may have. 

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