Need advice on insulation addition
I have recently bought a house that was built in the 1920's in south Texas. As you might guess, most of the time it is very hot outside. The insulation in my attic is very minimal and does a poor job of keeping the house cool / warm. I would like to better insulate the house, but know very little on the subject. Here is where I am on the project. I checked everything out and it looks like there is around 5 inches of blown in cellulose insulation. It looks as if the insulation is made of old newspaper and it appears to be pretty compacted. I have been reading around and it would appear that 5 inches is not sufficient, so I am looking to add. I am not sure how to go about this project... Should I:
1. Blow more insulation on top of what I currently have
2. Lay fiberglass insulation on top of what I currently have
3. Remove current insulation and blow in new
4. Remove current insulation and add fiberglass
5. Something else...
I am not afraid of hard work and just want the best for the house. Does any one have any guidance for me?