If they are whiteflies, they will fly off when you tap the plants.* The aphids will usually stay in one spot and suck the juices on the stems and veins of leaves.* Mealybugs look like tiny tufts of cotton.
When making your own insecticidal soap, be sure to use soap and not detergent or anti-bacterial soap, as those can harm your plants. Glad to know that things are better.
When weeding, the best way to make sure you are removing a weed and not a valuable plant is to pull on it. If it comes out of the ground easily, it is a valuable plant.