I shoot a .308 Win. rifle. Must of my hunting is done up state N.Y. Most shots are within 150 yards. I hunt for deer and sometimes bear. I use Nosler bullets. When do I use ballistic tips or should I use the partitions??

A partition is never a bad choice. Using the .308, at your range, the hornady bonded/interlocks and rem core lokts would do you a good job.

You are not going to experance the BT troubles that most report, as your not using a Manglem.
I'd recogmend the BT's for deer (no Tx heart shots, however) and the Partitions for bear. I've got somthing over 50 deer with 150gr BT's out of my -06 and unless there inside of 40yd and head on the bullet will go out the other side.
Set about 2.75" high at 100yd and you will be within 3" out to 265yd or so.

I think the BTs come into their own when their impact vel. falls below 2400fps. If you have a "long" shot of 150, I'ld stay w/ 150grNPs & be happy that you can take any reasonable shot.

I'd use a 150gr or 165gr Partition, and never look back...

Or you could try the new Accubonds, or a Hornady Interlock, or...

I'd just stick with what has worked best for you. I myself prefer Nosler Partitions in damn near everything though, gives you a little extra edge on black bear which can be potentially dangerous.