What should my first steps be if diagnosed with oral cancer?

Get treatment. Local disease is treated by surgery and radiation. Surgery is more common. Chemotherapy, like Cisplatin and 5-fluorouracil used before or during radiation is just as good as surgery and radiation in locally advanced disease. Recurrent or metastatic disease is treated palliatively with Cisplatin and 5-fluorouracil or paclitaxil. Patients with localized disease can have 75% 5 year survival.
Find an oral surgeon. That has experience, have tests to determine extent and stage, learn options for treatment. Oral (tongue, alveolar ridge, cheek, floor of mouth) does better with surgery at earlier stages than radio/chemo, which may be as good or better in oropharynx. Go to a center and speak to all disciplines to have questions answered.