There are really 2 ways to raise humidity. One is to get more water vapor in the air in the first place, and the second is to keep it there once it is there.
For the first, you can mist, use a water bowl with more surface area, put the water bowl in the warmer end of the tank, etc.
For the second, avoid using lamps and CHEs which tend to zap the humidity, and cover most of the screen top, or use an enclosure such as a plastic tub which doesn't have a screen top in the first place.
To know if it is "good enough" you need to have something that will accurately measure your humidity. Those dial gauges sold at pet stores aren't very good. I use an accurite (brand available at walmart) digital indoor/outdoor temp & humidity gauge, which is great cause it gives me warm side temp, cool side temp, and humidity.