1) First Step - Cleaning
Because I work in a greenhouse with many houseplants & potential bugs, I wash & sanitize all of my pots before planting in them:
I use a SOILLESS MEDIUM. It is full of minerals & will provide a light happy home for all of your little babies. You can buy it at almost any hardware or gardening store. I get the soil damp in a big container, and then place it in the trays ready for planting.
After my pots are cleaned & soil prepared, I gather all of my tools. I use old vinyl blinds for labelling, my seeds and a watering can. When you are planting 35 different types of tomatoes, labelling is key . . . . . you might think you'll remember, but you probably won't. or i don't . . . . use a sharpie so the label stays on when wet or dirty.
Now the fun part, I always use my own seeds. I get close to 100% germination, so I try to remember to put only one in each container, but sometimes I get a little excited (as you will see from my sprouting photos soon!)
Now, leave your labelled seed trays in a warm & sunny locale, and wait for the magic to happen