Lots of new gardeners this year! I am excited as many learn this useful skill.
This is the basic seed starting mix I have been using with good success for a good while now.
Wendy's Keep It Simple Seed-Starting Mix
4 parts compost or garden soil (Some sterilize their garden soil.)
1 part perlite
1 part vermiculite or sand
2 parts peat moss
Mix it up in whatever container you have on hand. Break up any clumps. Put it to use.
Happy Gardening!