The good news is - it's easier than you think. Style isn't about figure, it's an attitude. You can decide to have style.
Start with the two most basic things, a trip to the hairdressers and a new bra. Take a look in the mirror and smile. It's strange how, when you get older, boob height becomes important!
How's your makeup? As we get older our skin tone changes. I am also over sixty and Ive lost my freckles, sadly, my skin isn't a lovely magnolia color any more, it's just kind of pasty. Time for a new foundation or tinted moisturizer. Keep your skin well moisturized, your bust and hair under control. Look in the mirror and smile.
Next, look at your shoes. Find something your feet look good in and look comfortable. Black and brown shoes are conventional, red, oddly, goes with a lot and can make life simpler. If you're looking for one good pair - red shoes go with dark blue, brown or black, while black shoes - don't.
After that it really is up to you. A lot of style is attitude, so you need to be comfortable as well as look good. Keep looking in the mirror and keep smiling. When you get to clothes make sure they fit well. That's more important than anything, and one thing that can help you put an outfit together is to remember that two co-oridnating colors look good, but for style you need three. Even if you dress in all one color, as I tend to do, add a colorful scarf, if you don't like it round your neck, tie it to the handle of your (contrasting) handbag. And smile.