Thinning hair as we age is nothing new, it happens to many of us. I would recommend doing overnight oil treatments on your scalp to stimulate your scalp and encourage more growth. I like using the original version of WEN Tea Tree Oil, but if you do some research you will find other options as well. As for a styling product, there are several thickening products out there. I've tried a few. I liked one by Not Your Mothers, but right now I'm using something by Kenra. Paul Mitchell makes one and I'm sure other popular lines do as well.
If you want to go to a full system, you might look into Nioxin. My sister was complaining about thinning hair a few years ago and I gifted a Nioxin kit to her. She liked it and my BIL noticed a difference, but as soon as it was gone that was the end of it because my sister is a real tightwad.