Basic blood work including CBC, sugars, lipids, serology, renal function etc.
Hormonal evaluation like thyroid function, testosterone levels if warranted.
Checking the ovarian reserve in the lady with FSH, LH and AMH levels.
Ultrasound pelvis by transvaginal route.
Semen analysis for the husband.
Tubal patency test by means of an HSG.
Other tests like Prolactin, testosterone etc. depending on the clinical scenario may be suggested.