Things You'll Need
Self-leveling floor compound
Self-leveling compound is a means by which you can fill in cracks and holes in your floor without having to replace large areas. You may even find it prudent to cover your entire floor in self-leveling compound, especially if you are planning on laying a tile or wooden floor, which is very susceptible to bumps and divots in a concrete subfloor. Self-leveling compounds set quickly and can be sanded down to give you your desired finish.
Remove any dust and debris from the floor using a vacuum cleaner.
Roll a coat of latex floor primer onto your subfloor. This will ensure that the compound bonds with the floor.
Closely inspect your floor and circle any areas which are dented or cracked with a pencil.
Follow the manufacturer's instructions on the self-leveling compound packaging to mix the compound in a bucket with some water. Mix for two minutes only, as the compound will begin to set almost immediately and you need to pour it before it becomes too rigid to use.
Pour the compound into the indentations that you identified in Step 3. Leave for 10 minutes and flatten with a trowel. Feather the compound into the existing floor to ensure a seamless continuity.
Leave the compound to set for two hours before walking on it and for 12 hours before laying any flooring.
Sand down any bumps and lumps in the compound using a sander. Use a vacuum cleaner to remove any dust before you lay your flooring.