I love planting and am not particularly skilled in the art of patience. I start my planting in the house early, and that gives me a head start on summer crops.
Set up your greenhouse
Before you start planting, you need to establish a home for your seedlings. I have a indoor greenhouse. It is roughly 4'X2'X6' and has 4 shelves, with a plastic cover. I installed UV lamps to the tops of the shelves (with zip ties), and heating mats on the bottom to keep the soil warm. This seems to have improved the outcome of the seedlings significantly. I make sure everything is in good working order before bringing the plants into their new home.
Pick your plants
Look through your seed packages, or if you did not get your seeds from packages, you can look online. Usually in February is when I start my indoor seedlings, and I start with tomatoes, peppers, broccoli, chives, and onions. I have a schedule for my plants, starting some in February, March, and the last indoor bunch in April.
Start your seedlings
Once you've selected the seeds you want to start, get a seedling starter tray. I found the ones with a soft rubber bottom, are much easier to use when transferring to a larger pot while preserving the baby roots and are my preference for starter seedling pots. I use a regular potting soil for the bottom, and a seedling starter potting soil for the upper part of the pot. Place small finger imprints in each pot, and plant 3 seeds in each section. Cover with soil and water. place in green house and water daily. Within a week you should see sprouts in each of your sections. If there is more than 1 sprout in a section, pinch off (do not pull) all but the strongest sprout, leaving only one sprout in each section. Continue to water regularly.
As your sprouts become stronger, and larger, the roots are going to need more space to expand. I use small peat pots for young plants. Fill about halfway with soil and carefully push the plant from the bottom up and transfer the sapling to the peat pot. Add soil to the peat pot, and ensure the plant is packed in securely. Water after transfer and regularly. Monitor the plant, as it grows, you may need to transfer again from a peat pot to a larger pot.
Once the temperature has warmed up enough (each plant has different requirements), start bringing your plants outdoors during the daytime, and back indoors at night. Do this for about 2 weeks, to get them accustomed to the outdoor temperatures. After your two-week period, either leave them outside in their pots, or complete the final transplant to the ground. I keep my outdoor plants watered on a timer. They get watered once a day in Spring, and early summer as well as the Autumn, and twice a day in the midst of summer. Over watering can be just as deadly as underwatering, so be sure to adjust as necessary based on how wet the season is.