Shaking up your fermenter after you put the wort in there for like 5 minutes will aerate it. I use this: https://www.homebrewtalk.com/f51/cheap-easy-aeration-gadget-68218/. I use it to transfer from the kettle to the fermenter and from what I can tell it aerates it very well. You could also go with an oxygen stone and O2, but that costs money.
Cool, thanks for the link. I built one of the venturi injectors from that thread last night and tested it out. It worked great.