:*As a good general guideline, you can improve items to your skill +10. For example, a hammer uses blacksmithing, if you have 25 skill, you can improve the item to 35ql.
:*Blacksmithing is the most important smithing skill, followed by weapon smithing. This will cover all your tools and allows you to work faster and better. Black Blacksmithing is more important because your hammer and anvils use this and these tools need to be good to make the other smithing skills easier.
:*The better the quality of your tools, the more chance you have to succeed at imping. If your tool is significantly lower quality than the tool you are imping (say 30 points lower), your chance to improve the item is very slim. You will most likely end up lowering the quality of the item though fails & repairs.