Put a bit of silicon sealer, like you'd use around a tub or sink, over the spoke ends inside the center hub. This will keep the grease from migrating out the gaps and streaking the spokes as you drive.
Check the wear of the hubs and wheels by looking at them from the ends. If they feel sharp as you brush a finger across them or they're bend to one side, they're worn. If that's the case, and you're not replacing them, keep the same wheel on the hub. Otherwise the mismatched wear patterns can cause the wheel to end up being difficult to remove.
If you do replace worn items, it's best to replace a hub and wheel as a pair. If one is new and one worn it can cause the new item to show wear prematurely since the pressure/contact points of the 2 sets of splines won't match like they should.