Base training for half marathon

Hello,

I’m currently recovering from a marathon however I want to transition to focusing on half marathons. My next race is in October so I was wondering how should I approach keeping/improving my running for it until I start my plan.

I’m currently considering running 4 or 5 days a week but I’m wondering how miles should I aim for, how to increase mileage and how many speed sessions per week should I do?