want to view Changing of the guard on a Tuesday late August. Any tips?

We got there early and were at the fence next to the gate. We had to hang on to the fence because people kept trying to get our place. It was very boring in my opinion. The parade into the grounds is much more interesting to watch. If you can get a spot along the road at curbside, you will have a great view of the parade. Be prepared for a huge crowd. As far as how to get there, take the tube to the nearest station and walk the rest of the way or cab it early.
Once was enough for me. I enjoyed the changing of the guard at Windsor more.

Everything I've read about viewing the Changing of the Guard makes me think you have to get there very early to see anything. There is so much to do in London, are you sure you want to use what sounds like hours of your precious time for this? I think Rick mentions an alternative in his guidebook, but I don't remember what it is. I'll bet someone else does.

Before Internet forums existed, I had visitors who wanted to see CoG at BP, I thought it was underwhelming, tedious, a huge time muncher and a poor viewing position.

In August Buckingham Palace State rooms can be visited, I recommend you do this instead.

What I'd do for CoG, from the official Troop Movements web site, is go to St James's Palace and Wellington Barracks where they start/finish, also separately Horse Guards Parade for their mounted changeover. In photos below see how close you are to the horses.

Horse Guards rd is very near the Churchill War Rooms, that is worth a non-rushed visit.

Windsor also has its own CoG.

https://www.householddivision.org.uk/changing-the-guard-movements

https://changing-guard.com/queens-life-guard.html

I like to watch them form up in front of the Wellington Barracks on Birdcage Walk. If it's at 10 (can't remember the exact time), then be to the barracks area at 930. You can watch them being inspected and hear the band play. They then march out of the area exiting on to where it says Spur Road, and then across into the Palace forecourt.

https://goo.gl/maps/uHrmCXvkoc5SGZG57

(Well, my pin in the googlemap didn't copy so they form up in the big paved area between where it is marked The Guards Museum and Spur Road.)

I also like the changing at the Horse Guards but have not done that in years and years.

The crush in front of the Palace is awful and really there is not as much to see as you think there will be.

As an alternative, you might want to catch the changing of the horse guards, Monday through Saturday at 11:00. It's similar, but with cavalry! Much less crowded. https://www.visitlondon.com/things-to-do/place/484414-horse-guards-parade

Last time I was there, I walked past the enormous crowd in front of Buckingham Palace (90% of whom could not possibly have seen anything from how far back they were standing and the gates blocking their view) and went to the Royal Mews, where they keep some of the Queen’s horses, cars, and carriages used for special occasions. I thought it was really interesting and I had the place to myself! It’s pretty small, so I was finishing up by the time crowds who had been watching the Changing of the Guard started coming in. Nice gift shop, too.

I know that this is not what you asked for, but if you are going to Windsor Castle, they have a changing of the guard and I went to that, got there early, waited by the rope and got to see their changing of the guard and got some really great photos. I enjoyed it. It filled up but as I was already touring the outside of the castle, it as easy to get there to see the changing of the guard. You may want to consider that if going to Windsor.

I did not see the changing of the guard at Buckingham Palace but I did buy a ticket to tour the inside of the palace and the Queen's Gallery and the Mews and spent the whole day there which was amazing at the end of August a few years ago.

I much prefer the Horseguards ceremony - you are right up close, there are horses, shining breastplates, and much more of a spectacle - easier too.

To view the Changing of the Guard in August, it would be a really good idea to get there as early as possible. Once you find a good vantage point, don't leave it! Keep in mind that when the event is happening, you'll be surrounded by people so may not be able to see much. For that reason, up against the fence is a good location. Others will be using this same tactic so you may have to get there really early!