I have become a great believer in modules and except for carrots and parsnips start everything off in them. I also have a greenhouse, which I have to say is an essential for large scale sowing, but many find a window sill works just as well. I am also thrifty, tell me a gardener who is not!, so my modules can be simple in the extreme. The basic module is nothing more than a paper tube formed around the off cut from a kitchen waste pipe and held together with a single staple. I've found that twelve of these tubes will fit comfortably in a 2ltr ice cream tub, a good reason for putting ice cream on the shopping list. Bigger modules can be recycled pots, the sort you find in bins outside of garden centres, and soft spread tubs for sowing small amounts for transplanting when big enough for their own module. Remember to drill holes for drainage.
Next thing to consider is compost. Bought compost is fine, after all if you calculate that most seeds take 7-10 days to germinate and may be growing for four weeks until big enough to plant out, the six weeks of nourishment commercial compost state on the bag will do nicely. Myself, I like to use my own compost. It has been maturing for the last 12 months in those plastic darleks, they sell through the council cheap, and is now lovely crumbly and brown. To this is added leaf mould which has been open to the elements for the last twelve months, and sieved to get best out. The rest goes back for another year. Lastly, sharp sand is added for drainage. It is mixed in a ratio of two parts compost, one part leaf mould and one part sharp sand.
With the paper tubes, first put a small amount of the mix in and ram tight with a suitable tool, mine is a piece of dowel that by luck is just the right size. This forms the base of my module so the compost will not flow out the bottom when lifted. Next fill to the top and lightly tamp down leaving 1cm for the seed. Place two seeds on top and then loosely cover to the top and water well. That should be all the water it needs but if it does get dry in the greenhouse, even in March the temperature will reach 28-30C when the sun shines, water from the bottom. Two ice cream tubs will sit in a seed tray and if you line with plastic will make a nice little reservoir for the water. Label your tub and cover with value range cling film and wait for the magic to happen. If both seeds germinate, well you can pull out the weakest, but waste not want not I'm just as likely to transplant it to a spare tube.
This year I'm trying out soil blocks. I came across them in a book by Eliot Coleman called 'The New Organic Grower' (chapter 13) and was intrigued to find that the moulds he used were made in England by a company called Ladbrooke and sold here through the website www.blackberrylane.co.uk. Basically they are cubes of compressed soil/compost mix that have a depression in the top for the seed. They suggest leaving the seed open to the air as oxygen aids its development and water using a spray mist. The principle is the same as my paper tubes in that the seedling can be planted out without disturbing the roots but the blocking mix is different requiring peat to hold it together. The recipe can be found in the book (1st & 2nd editions) or on the website, but as they are all different in some way Ive done my own thing. I have also made my own blocker out of scrap that end up in shed 'because they may come in useful sometime' and guidance from Youtube. Isn't the web wonderful.
My last tip come from Monty Don and Daphne Ledward and cover garlic and onion/shallot sets. I know these can be planted in the Autumn but last time I did that it was so wet they rotted so now the garlic is started in pots and planted in March, thank you Monty, and the sets are placed in trays of damp compost until they have a good root system. When the time comes to plant out the compost just falls away and they can be planted into shallow drills with the earth being pulled back over the roots. There is less likely hood of birds pulling them out or roots pushing them out and they will mature just a quickly as autumn sets, so thank you Daphne.