Fallout: New Vegas

It's possible to do this achievement almost as soon as the DLC is loaded, before you've gone to the Sierra Madre. Once the DLC is loaded, you can access the "Abandoned BoS Bunker" near Nelson/Forlorn Hope. Go there, and save your game, with a hard save.

When you enter the bunker, continue down the stairs, as if you were going to start to DLC. Open the door that gives you a warning message, but DO NOT WALK ALL THE WAY TO THE NEXT ROOM. Doing so will force you into the Sierra Madre, and you may not be ready yet. Instead, hang your first left, and hack the computer there.

This will open a little room formerly occupied by a BoS knight. In the corner, there is a vending machine. It will dispense food for Sierra Madre chips. It will also give you chips, for cartons/packs of cigarettes.

Cartons and packs of cigarettes are relatively low-weight/high-value items that a lot of people pick up, to sell to merchants. So you might already have a few, or might have recently sold a few to a merchant. Go buy them back. Alternatively, if you've been let into The Strip, and the Lucky 38, the 38's casino floor has a ton of free cartons of cigarettes. there should be enough there to easily net 500 chips.

I made 845, in one shot, from a few I had sold to a merchant, and the ones in the lucky 38.

You can get this cheeve real easy. Sierra Madre chips are EVERYWHERE. Check the fountains, cash registers, and file cabinets. Look around and you will find the chips. Just play the Dead Money DLC and keep a sharp eye out for Chips, you are certain to get this,

Probly the easiest way to get this achievement is just to pick up the DLC's snowglobe which is worth 2,000 Sierra Madre chips and are instantly given to you upon picking it up.

The Snowglobe is located in Salida del Sol North. After entering Salida del Sol North from Salida del Sol South go down the stairs in the room your in and then through the hole in wall at the bottom. Right after going through the hole turn right and follow the wall all the upway the stairs and stop at the top of the stairs and turn left. cross the roof of the archways and then follow this path until you can cross over to the left via another archway's roof. Turn right after crossing and then head straight down the path and through the hole in the wall on your left. You will enter a small room and the snowglobe will be on a crate to your left immediately after entering through the whole in the wall

Note: occasionally the snowglobe glitches for some people and can not be obtained until exiting the vault at the end of the DLC

There are many ways to get this achievement:
1.) As soon as you enter the BoS Bunker to start the DLC, there will be a room to the left (requires hacking) that once housed a BoS Knight (you'll find out whom later). In this room there is a funky-looking vending machine that will dispense goodies for Sierra Madre chips (you don't have any yet) but will also dispense Sierra Madre Chips for packs/cartons of cigarettes. If you have enough on your person, or have some stashed away, this is an easy way of getting the achievement without committing to entering the DLC... Also a great way to get the achievement if somehow you went through the DLC without collecting the required Sierra Madre Chips.

2.) Once entering the Sierra Madre Villla, just start looking. These chips are everywhere: on the ground, in fountains, etc. As you walk around, just pick them up!

3.) As the story progresses and you start going through buildings, check all the file cabinets; specifically the cabinets in the clinic when you are rescuing/finding Christine, as there are dozens/scores laying around in there.

4.) Once you have Christine and you erm.. talk to her a bit, you'll find that she can counterfeit chips using a FISSION BATTERY and SCRAP METAL. She will teach you the perk, and from then on you can counterfeit your own chips.

5.) After gaining access to the Sierra Madre Casino you'll be tasked with turning the power back on. Once this is completed, you can gamble at the slot machine, play blackjack or roulette.
With only a few chips starting out, you can win the required amount of chips for the achievement to pop.

6.) At the cashier (once turning the power on in the casino) you can trade PRE-WAR MONEY for Sierra Madre Chips. I tend to go through the entire game and collect PRE-WAR MONEY as it has a nice value:weight ratio and is a nice way to get some easy cash. If you do the same and have a large amount, you can just trade it for the required amount of chips.

An unrelated topic, but worth mentioning:
If your LUCK is very high, I would greatly suggest playing the slots in the Sierra Madre, maxing out your winnings, cashing out for PRE-WAR MONEY, then taking them to the Vendortron at Gun Runners. - I now have over 200,000 chips (sure its a game-killer, but I've already killed-the-game)

This achievement is already easy peasy, but if you want it even faster, just rack up 50 (you can actually rack up less.. but I picked that number because it goes into 500 a perfect 10 times), but anyway. To save time and to keep you from digging through every fountain, cash register, drawer etc. Just rack up about 50 of them and go into your inventory and drop all 50 of them. They'll condense down into one single chip worth 50 chips. Just pick them up and you'll notice your achievement progress just went up to 100 then 150 then so on. Just rinse and repeat your dropping and picking them up and you'll be there in literally less than a minute. I found this to be, without a doubt, the easiest method out there.

However, this doesn't make you have a total of 500 coins. You'll still have 50, but the game registers you picking up those 50 or however many you decide to drop as extra toward the achievement.

In the Dead money DLC you can find a snow globe when you collect it it gives you 2000 Sierra Madre Chips, the snow globe is located near Dean's Secret Stash in the upper levels of Salida del Sol North. From the southern-most entrance to Salida del Sol South (inside a house in Salida del Sol North), proceed down the stairway and out to the street then look behind you for the entrance hole in the wall above. This area can be reached by going up the stairs located around the corner to the southeast and following the rooftops back towards the hole.

easiest way i found to do this is just scavenge about. you'll find lots of it in your gameplay, one way or another.

there's another way: you can try and find the sierra madre snowglobe, it'll give you instant 2000 chips just for collecting it.

edit: you can find the snow globe in the Salida del Sol North area. (Not in the Villa like the game's description says).

Once you enter the Salida del Sol South area, make your way to the Salida del Sol House. Go down the stairs and outside. Then turn around and look up once outside to see the big gaping hole in the wall - it's in there.

just make a right from there and go up the nearest staircase and jump onto the roof from there.

Worth 2000 Chips

For this achievement just be patient and don't spend ANY siera madre chips at the vending machines. 

Try to use food you find and create siera madre martinis (unless you dont want to get addicted to them, which you will, but its worth it as health is limited) to heal and save stimpacks for when your really low.

Search EVERYTHING and this won't take long. Lock pick skill of a 100 will make this go faster as some big stashes require it. 

I got this before the gala event happens.