Well, I would certainly clean the railheads using your favorite track cleaning method. My self, I use Goo-gone, but you will find a lot of people who are agin it. Clean the stock rails and the points where the points contact the stock rail. Many turnouts rely on point-to-stock-rail conductivity to pass power onto the points. Some turnouts have auxiliary electrical contacts on the points, they could stand a cleaning too.
I might check them for flatness, lay the turnout down on something good and flat. It ought to lay flat, no air space under it, and when you sight down the rails they should NOT show a bow, a dip, or a twist. If the turnout is not flat, you can bend it flat with just your hands.
Then I might use my NMRA gauge to check track gauge, flange way width and depth, guard rail spacing.
Finally, if you are into hot frogs, it’s easier to hot them up with the turnout on the bench. Me, I don’t bother, my trains run fine over dead plastic frogs.
I drill a 1/2 inch hole thru roadbed, sub roadbed, and table top to let the Tortoise operating rod reach the tiebar. Use a 1/2 inch twist drill, a spade bit will make a mess. Do this BEFORE laying track. Then put the turnouts down first, centered up over the Tortoise holes, and route the flex track to mate up with the turnouts.
You can put turnouts down with just latex caulk for stickum. Taking up a stuck down turnout is possible, but messy and tedious. Track nails into wood road bed hold the best, in fact they hold so well that I don’t need the caulk at all. Track nails into Homosote are just about as good. Track nails into cork roadbed don’t hold that well, although they hold well enough to work. Track nails won’t go into plywood, the glue layers are so hard that the track nails bend before piercing the glue.