Acrylic drys darker,i dont know how many times i forgot this and thought i mixed properly only to come back when the paint is dry and it was a lot darker.

I have worked with both acrylics and oils. I love the look of oils, and how smooth oil paint looks. But I can't handle the strong smells of the thinner to clean it, so I refrain from using it.

I have been working with acrylics for a long time, and I really like how convenient it is to work with. It doesn't smell and it's really easy to work with once you understand how it works. I know a lot of people complain about the fast drying time, but this is why I love acrylics. I tend to work fast, and I hate waiting for drying times. But then again, it's sometimes a pain that it dries so fast, especially if you want to blend. But I've learned to do layers at a time to blend, and to also work fast. There are also mediums that slow down the drying time, but I don't use that. I tend to water down my acrylics and just keep layering until it looks blended.

I have also used water based oil paint. Since it's water based, you can use water to thin it down and to clean it up. It's not as toxic as regular oils. It takes awhile to dry like regular oils, and the colours are really vibrant like them too. I really like working with them as well

I have never used gouache or caseins, and don't have enough experience in watercolours or tempura.

It really depends on the person on what kind of paint is right for them.

Insofar as the way acrylic paints are packaged, there are tubes and bottles. The tubes usually have thicker consistency, while usually thinner with bottles. I think the tubes are more economical in that when it runs low, you can squeeze it to get some more paints out. By contrast, once the contents inside the bottles run low, you have to scoop it out which means potential for more mess.

You can vary the thickness of acrylic paints with water, matte medium. If you are going to apply series of thin transparent layers, as in glazing, then you will most likely need a matte medium. If you need to slow down the drying time, then consider a bottle of retarder. Only a little bit of retarder (no more than a few drops at the most) is needed per use, so do not overdo it.

With a plenty of water, you can also use acrylic paints to make light washes somewhat similar to watercolor, with an exception than once it becomes dry, then it stays permanent.

Since a lot of people have already commented, do you have any questions that a some of people couldn't answer? I could try to answer any questions you have, instead of just responding with a lengthy paragraph about my acrylic experiences... Specific questions I could help you with though! So, feel free to ask. ^^

Ok, so from the top for my Acrylic painting advice.

Saying that oil is better then acrylics is so opinionated, I feel like throwing shoes like that Muslim guy to George Bush. I feel like Acrylics is much easier to deal with, because its pretty straight forward. You can make it thick like oils or thin and pale like watercolors. You also are alloe to only use water too.
Fast drying time can be an upside or down side. Its cause because acrylics are water based mediums, meaning the main thing thats drying is the water in the acrylics. You may have to use more because of the fast drying time. You should get some slow dry and retarder, to slow the process down. Make sure to read the instructions. Sta-Wet pallete is benificial, with a sponge in it. This will also help slow the drying time down. And even a spray bottle could also help. Spray on the acrylic paint, when you are finished and need to use it again.
Some towels are helpful. Paper towels is ok, but the better stuff is shop towels, because they are softer and better for the brushes.
Get a metal pallet knife. They mix paint better then the plastic.
Easy clean up, but very hard to get out of clothing. You should Wash right way with hot water when you get stuff. Acrylic is close to a plastic and so, alot of hot water, hand lotion, and ivory soap should help. Powder soap also works really well because its like sand paper. Careful of the hot water when doing this. Maybe set it to warm. This goes the same as when your washing your brushes. And also never let paint dry on your brushes. That will ruin them.
For brushes, don't get the really cheap ones like the crayola isle. Thier bristles are not glue properly. You also have the artistic license to use other tools to paint with, such as your pallet knife, cardboard, sponge, toothbrush, etc.
For colors? I can't remember them right now which ones you exactly need, but the brands you should get are liquidtex heavy body or Golden Brands. If its too expensive, just start with the student liquidtex.

Oils, because of its chemicals, you have to make sure you dispose of it properly and cleaning your brushes properly. Thats the only down side is that if you don't do it properly, especially in a public place, you can be fined. You can't thin oils with water unless its water based. Other then that, you have the liberty of never drying, and so, very easy to blend.

So, either way, I don't think it matters what you start with, other then be aware of what the medium does. For me, oils are not the best thing ever in the world. I don't want to deal with chemicals and have a bad habit of putting things in my mouth.