Again reinforcing the grease recommendation. Too much is barely enough. You want the excess to ooze out so it forms a bit of a seal that way.
Also, you can get a corregated plastic sleeve that goes into the bottom bracket shell between the cups and helps keep crud and water away from the bearings. These things are less than $1 at almost any LBS.
Use the Suguino and when it dies, then get a sealed bb.