How to get a teaching assistantship
I don't know how to post things after people have replied to them. Technology: it isn't my forte, I guess that is why I study history. So, ifallirise, i've tagged you so you'll get this.
First thing you should do is look at the funding available for the program you are interested in. It should tell you about any scholarships, assistantships, and fellowships available - as well as what you need to get them.
If you have any extra questions, or if the website does not provide information on these types of funding you should contact that department.
Also, it's easier to get in if you speak to professors or the director - especially the director. It shows that you are interested and willing to put in the effort.
Make sure you have a good curriculum vitae, and a 3.5 or higher GPA in my case. Good GRE scores (or which ever test you need to take) helps bolster your chances - mine were decent/middling, but I have a really good CV to make up for it.
If you have any other questions just throw an ask my way :)