The second place (see the first place in my post about Jonanjima) near to Haneda Airport is Keihinjima Tsubasa Park. I’ve only been there once. I’m not sure why, as looking back I got some good shots there, despite the wind direction meaning I was largely getting shots of planes taking off and I tend to prefer taking pictures of planes landing. Perhaps it was also the fact that I was there at about dawn, so there was less activity, that I associate it as not as being as good as Jonanjima. It could also be that I know that I can get more varied shots (not just of planes) at Jonanjima that means, as I tend to only have a bit of free time when in Tokyo, that I tend to go back there rather than go to Keihinjima Tsubasa Park again.
In terms of getting there, the easiest access point (if you don’t have a car) is via Showajima on the Tokyo Monorail. From there you can walk.
If you have data then you can use an app like Flightradar24 to see when planes are landing or taking off.
Keep an eye on planes after they have passed you as you will find that many will circle above the airport gaining altitude, so even with a 300mm lens, you can get some interesting shots of the planes turning and going off to their destination.