The base of your Regency Gentlemen’s clothing is a cotton or linen shirt. On your legs are stockings, breeches or trousers and boots or shoes. On your top half you would have a cravat, waistcoat and jacket over the shirt. When outside a gentleman would wear a hat either a beaver or stove pipe (both early types of top hat) or bicorne hat, and possibly a caped greatcoat.

Shirt
Shirt pattern

Breeches
Breeches pattern 1
Breeches pattern 2

Waistcoats
Waistcoat 1790-1820 Sewing Pattern

Jacket
Jacket with 5 Collar and Lapel pattern
Jacket from 1800 pattern