Here's the website
https://www.shiphelp.org/ to help you find the Medicare-funded counseling program near you. Mine is through the county extension service, staffed by trained volunteers. I signed up for a group info session 4 months before my 65th birthday, then a one-on-one session with a volunteer. I knew from the group session I wanted Supplemental, not Advantage. Once I understood the A-N plan structure, it was easy to make that choice then compare providers in my state. I went with one with a good track record in my state and an easy-to-navigate website.
Before I made my choice, I called my doctor's billing office to ask if they had a preference on supplemental providers. They said, "Medicare makes it so easy for us. We know what we're going to be paid and when because the Medicare Plans govern payment, not the providers. Choose whoever you like."
The information sessions in my area are once a month, with volunteer appointments available during open enrollment. But demand is so high, those appointments are booked up weeks in advance.
I have friends with long-time insurance agents who told them, "Medicare is just too complicated for anyone to understand and you're getting forgetful, aren't you? I know your husband took care of all those decisions for you; let me do that now and spare you the trouble." and sold them Advantage plans. They have worse coverage at a higher cost than me. I've dragged a few to a information session. Fortunately they didn't have to confront their agents for the switch; it's all done on-line. One got a call from her agent threatening to "tell your kids what you did". Scum.
The website above is not the "counseling" services that offer you a free Medicare seminar with lunch or fill your mailbox with flyers. Those are Advantage plan marketers. The SHIP will be through an Area Agency on Aging or Senior Services or other not-for-profit or government entity. It's unbiased information available to anyone. If it turns out you're eligible for assistance, they'll help but there is no income requirement to access the information.