Well ground handling would be the first step. Maybe it'd be a good idea to keep your two horses together at first, like stalled nearby, and slowly wean them off of the idea of "we are joined at the hip" Pull each one out of the stall to groom and such.
I'd focus on one at a time primarily because you want your horses to be okay with being away from each other .. and if you put your efforts into one horse until it gets there, then it's much easier on you and your horse as they get one-on-one introduction . They'll feel more confident with their herd leader (you), and they both will know that it's fine to be without their herd buddy.
After they are fine with being handled away from each other, then I'd start working on the ground teaching them basic concepts. Sack them out with pads and the saddle and teach them about pressure and release. Teach them to lead and ho and tie and all that good stuff. Then build a lunging schedule. You should always start out small. Build up what you do during that lunge session but don't overdue it. Lunge bare and then lunge with a saddle. Hand walk each horse around the barn and maybe down some trails if they are close by. All the while your goal is to make sure your horses are RELAXED.
I wouldn't start riding until they are confident on the ground without the other horse nearby. Then since you've been lunging and getting each horse ready to wear a saddle, it'll be much easier for you to hop on and start small with walking courses and learning about cues.
But the basic idea here is you want to kind of give them a huge refresher. You haven't been in a saddle for awhile either so don't push too much at a time. Make sure they feel SAFE, are RELAXED, and that they are FOCUSED.
As for you, I'd start with stretches before you ride because I am sure you will have sore muscles for awhile :p
Hope I helped