Pick a vertical first, don't try to do everything. Dating, sweeps, gaming, whatever interests you. Then pick one traffic source, start with something beginner friendly with low minimums. Set up a tracker from day one, some have free plans. Apply to a CPA network, talk to your AM and ask what offers convert in which geos. Start with pop or push traffic, cheapest way to learn. You'll lose money at first, that's normal. Focus on understanding the data, not chasing profit in week one.