Get together enough greens for however many people you need to serve. Try not to use only iceberg lettuce, its the least flavorful and has the least nutrients! Romaine is great, and red leaf adds nice purple color, and butter lettuce has a lovely soft texture. Try them all!
Throw in all your chopped veggies, tomato, cucumber, zuchinni, whatever...then take a handful of your pitted olives and, before you throw them in, hold them over the bowl, and crush them in your hand. This method accomplishes two things, it gets them into smaller pieces for eating, and releases way more of their flavor than slicing them. it crushes the flesh and releases their oils.
Feta cheese, as you may know, is very crumbly and pretty salty. If you've never tried it before, this is what really makes a salad GREEK! Just pinch your cube of cheese gently over the bowl and it will crumble into bits you can mix into the salad. If your not to sure whether everyone having salad is willing to try it, you could crumble it into a small bowl and put it next to the salad as an optional garnish.
Depending on how big your salad is you will need 1/4 to 1/2 cup of oil, and 2-4 tablespoons of lemon juice. I like LOTS of garlic, so I put two large cloves in mine, but this item is also adjustable. Crush your clove to release the flavor and dice into tiny bits, or you can squeeze it through one of those garlic squeezers. (but I always feel like some of my clove stays stuck in those) In a small bowl mix olive oil, lemon juice, garlic, about 1/4 teaspoon onion powder. Shake a nice tablespoon or so of the oregano into your palm over the bowl, now with your other palm, crush up the herb as you let it fall into the dressing. This again releases the flavors that are trapped in the dried leaves and gets them to your taste buds!
Wisk all this together, salt an peppa to taste. You can leave the dressing in the fridge to blend until you are ready for dinner, or you can even make the dressing the day before a big dinner party...don't ever add dressing to your salad ahead of time, cuz it wilts your greens and runs to the bottom of the bowl. toss it in right before your guests or family sits down to eat it!