Buy the bearings in quality kits.
Use a good quality bearing grease made for high temps and disc brakes. Get a few different types of punches to drive the races out of the hubs.

If they are not giving you any trouble at this time look at your front brake pads and if you have ....say...40% remaining consider doing them then sence all the breaks must be removed to do the front wheel bearings.

If you just had new brakes put on recently, well try not to get them all greasy.....