Adding to the GP, you just need to have a thick skin, and not take rejection personally. It's a fact of life in this environment. Regarding the venue and costs

Adding to the GP, you just need to have a thick skin, and not take rejection personally. It's a fact of life in this environment. Regarding the venue and costs, in CS, some conferences are better venues than most journals (impact wise, at least), and attending one might be a good way to know the people in the field. In any case, you'll be expected to pay for the registration and present your paper, too.