"Please help me buy some things."
I'm doing the checkpoint test, so I don't know all these words, but I knew "Please", "Me", and "Things" and 一些 looked like it could mean "things," due to the 一 and I guessed 买 for "buy" and "帮" for help and put the words in an order that made sense, expecting to lose a heart, but instead got it correct!
It's very informal to leave it out. i.e. you mean to say whether this is accepted: 请帮助我买些东西 Generally speaking you would say it that way to people you're familiar with. It's not unheard of to say it to strangers, but it's very informal and you generally wouldn't speak like that with people you don't know.