What’s the best way to level out wood floors in order to install laminate flooring?
I have unlevel wood floors and want to install laminate Flooring. Was told that I need to level out the floor but what is the best, least expensive way to accomplish this. I have tried raising the floor in the low spots but that did not help. Thanks 
I would use the powdered form and mix it. Also depending on the product you buy, you may need a primer which allows the leveler to bond properly to the floor. when you pour out the leveler it may be helpful to go over it with a straight edge following the high spots. Another suggestion is to sand down high spots, as this may minimize the amount of leveler you need.
What type of sub floor should I install under vinyl flooring?
you can buy liquid floor leveler from your local mega depot,it comes in pre mix buckets or bagged dry (just add water)50 pound bags.Just dump it out on the low spots and trowel it smooth.
References :
I would use the powdered form and mix it. Also depending on the product you buy, you may need a primer which allows the leveler to bond properly to the floor. when you pour out the leveler it may be helpful to go over it with a straight edge following the high spots. Another suggestion is to sand down high spots, as this may minimize the amount of leveler you need.
References :
Hi
If you put anything waterbased on to wood you could get big problems as the water will seep into the wood. I was told to use plywood or something like that all over the floor, it worked for me
References :
A common method is to use sheets of hardboard. Failing that there are floor levelling compounds, but they are not very good on old wooden floors where there are gaps between the floorboards.
Wickes produce a leaflet which explains how to lay the boards, including hardboard sheets and underlays. Don’t forget you will probably have to remove and plane doors since they won’t open over the new, higher floor
References :
http://www.wickes.co.uk/Good-Idea-Leaflets/Good-Idea-Leaflets/pcat/53flooring