General

In addition to what the others have said, you might want to look into the process of "glazing" before doing opaque painting with the acrylics. Get your values down with conte, add a light gesso coat on top of that to seal it, then bring color in slowly over the whole canvas with loose, watered-down brush strokes. It's pretty easy to get lost if you go right for heavy brush strokes.

gesso your canvas

@SirSoar: it's the single white layer on fresh canvas.

@Doutei

Is gesso what makes the surface white? Or is it prepackaged like that @_@?
Here's what the labeling says: Archival, acid-free, Medium surface, Titanium acrylic gesso primed

As for the paint to water ratios, water should be 50% or less in comparison to the paint itself correct? This affects how opaque or how transparent it is from what I've read.
Thanks for the tips!

Normal gessoed canvas don't absorb water, watch out for that.
The paint itself dries fast already, does not come off clothes either.

Make a colour palette and know your paint ratio.
Once the pain dries, the color will be perceived differently from how it is wet. It may be darker/ligher.
Try to finish one area of painting in a single sitting otherwise save your current mixed palette by spraying water ontop and wrapping it with plastic sheet on top.
Make mistakes = just work ontop of it after it dries.
White on dry will completely block it out, also makes way for lighter colors without dirtying them like yellow.
Run out of white, use gesso.

layers.
More painted layers = low chance of ripping.

@Wanton
Ahh, okay...I'll be experimenting then~ I'm truly a complete beginner in this so thanks for you help!

@SirSoar if you're lightly sketching in pencil, it depends what kind of painting technique you'll be using and what colours. If you're going to be painting thick: Some colours lack pigment, so even light pencil markings can be seen. An example is yellow. I can't remember what other colours lack pigment, so sorry about that. But most colours can be painted over light sketches. If you're going to use the paint like water colour, then you'll have to be careful about how much you water the paint down. Like I said before, you have to be careful with the paints that lack pigment. Using the water colour technique on canvas is horrible, I don't recommend it at all, because the canvas absorbs the paint and the colours turn out ugly. But if you like the effect it makes, then go ahead. Im not sure about wetting the canvas and then painting it, thats something you'll have to experiment with the paper.

@Wanton

I already have what I want to draw~ Can I lightly sketch in pencil on the canvas or would that show through? Also, do I have to coat the canvas with water before painting, or is that just done with each individual paint?

You can treat acrylic paint in two ways (ones that I know). You can water it down and use it like watercolour, or use it with less water and let it be thick. Take note that acrylic dries very fast. How do you start? Make some thumbnails of what you want to do then paint it dooooiiii. If you're still scared then you can do some test runs with the paint. Just paint on the surface of a piece of paper to get an understanding of how the paint works.