wig caps are certainly a major help in containing your hair. I got mine from katie blair's website, although you may find better ones elsewhere(I honestly dun know).
since you've said your hair is rather long, I believe you may want to try swepting it all back into like a ponytail and then slide on the wig cap(or you could try the wig directly, but shorter hair strands can still poke out). if you can't get a wig cap, I may be able to lend one but its black so it may stand out.
the main trouble I have with wigs myself, is really getting them secure on my head. since my haku wig is heavy in the back, it slowly slides in that direction.......