A lot depends what you are getting started? If you have limited space key things to get going early are peppers, tomatoes & aubergines which need a head start to crop in UK, I start these in 9 or 15 module trays on a sunny windowsill I use one row per variety as don’t forget that you will need to have space on the windowsill to pot them on a couple of times!
Other crops I start in a sheltered grow house in a similar way. Exceptions being Peas in a 6 module tray and beans in old toilet rolls
Hope this helps.
