Seeds + sprouts < 1in:

Keep soil moist (dark looking). Water often (~1 / day ?) but you don't need to give it much water just like a little dribble so the surface of the soil stays moist.

Sprouts > 1in:

I'd water less and give it more water each time you water. Like once every 3 days maybe like 1/8th cup or so? Doesn't take much. Just don't let the soil stay dry for too long. Biggest sprouts really only need it once a week or so.

Thinning

When the taragon gets bigger (~2in), pick the biggest one in each section and pull out all the rest. Same for the basil and mint. When oregano gets big, do the same but maybe leave like the 5 biggest sprouts in the pot. As long as they are not all right on top of each other, it should be fine. Stevia shouldn't need to be thinned.

Misc.

If water leaks out the bottom, you've given it enough stop!
If that sweet pea dies, oh well don't worry it was dying before I left.
If anything else dies :/ oh well