firstly

ensiksi, ensisijaisesti, ensinnäkin puhekieltä In the first place; before anything else; first.
(RQ:Schuster Hepaticae V)

Firstly, I continue to base most species treatments on personally collected material, rather than on herbarium plants. (..) Secondly, I continue to base my concepts on intensive study of a limited suite of collections, rather than superficial study of every packet that comes to hand.