@Fracisc You can use this one that I have attached. I have used it several times, and provided all the LEGAL rules for things the designer/client must provide/do
The contract depends on whether you are going to outsource work to a freelancer or getting a outsourced work from a client ? Anyway there are lot of standard NDAs available online that you can download & modify to suit your needs.
Make sure you have something that says you hiring for that project and are the owner of all the intellectual property developed and he is assigning you all intellectual property rights, if any.