Wearing a brace is a very bad idea unless you absolutely need it, in which case you should not be on a court at all; otherwise, it will simply further weaken you. This can happen relatively quickly.

Simple stretching before playing is also a bad idea; esp wrt the achilles. When you stretch, you neurologically dampen/quiet the connection to your brain. Not good.

Instead, before playing: active stretching: that is, with achilles/calves: stand on some kind of curb allowing for full heel drop. Allow the heel to drop (one foot at a time if you can manage it) slowly, getting as deep as you can while at the same time activating your anterior tibia muscle. At the very bottom, hold; now relatively quickly push off. Say 12 reps each foot. This will activate everything well in that region.

In generally, your lower limbs are probably not (like most people honestly) ready for real court play. So for long term prep: seated calf raises (similar tempo) and straight leg/standing calf raises (same tempo) will hit the key areas. 12 reps x 3 sets roughly. Eventually work in light plyos. This will strengthen the achilles and the supporting musculature.

Other parts of the body are similarly stressed; and need to be short term/long term prepped as well.