Before sowing flower seed, read the packet for sowing season, depth, temperature and any special treatment. Seeds that look similar do not necessarily germinate under the same conditions.
Prepare the containers, labels and growing medium first. Once a tiny packet is open, it is easy to lose track of where one variety ends and the next begins.
Label before you sow
Write the plant name and sowing date on a label that will remain legible when wet. Keep the packet or photograph its instructions so you can refer back without guessing.
Choose a container that will drain and can be moved without spilling the surface. Follow the stated sowing depth; burying every seed beneath the same thick layer of compost is not a reliable general method.
After sowing, check moisture gently and keep the tray in the conditions specified for that plant. Do not dig into the surface each day to find out whether something has happened. A clearly labelled tray with its original instructions gives you a better basis for deciding whether to keep waiting or review the conditions.
The RHS indoor seed-sowing guide confirms that sowing times and seed preparation vary. Check the packet before soaking or covering seed; a treatment useful for one species is not a default step for the next.
Related reading: Sowing Flower Seeds: Preparation, Depth and Seedling Care.