Know your pup!
To be successful at socialisation and environmental conditioning, it is absolutely vital to know your puppy and understand them when they are trying to communicate with you. Since they can't speak, they do this with their body language. A person who understands puppy body language is able to advocate better for their dog, support them in uncomfortable situations and help them when they are in need.
Have a good look at the picture below to crack the doggy-code!
Source: rspca.com.au
What are their favourites?
Get your puppy to test different kinds of treats and toys for you, and try to find which ones are their favourites! Always carry these favourite toys and treats with you for socialisation and use them to reward your puppy. There is no point carrying treats or toys your puppy doesn't love or not especially interested in. Sometimes during socialisation, you want to pair something amazing to a potentially scary stimuli to counter-condition your puppy; but you'll never be able to comfort them or impress them with something they don't actually want!
Also be mindful of how many and how big treats you are handing out to your puppy - too fatty or rich foods can cause an upset tummy. I personally recommend plain, poached or airfried chicken breast as it is a very lean and easy on the stomach. Occasionally we see some dogs being allergic to chicken or other proteins, so make sure that their preferred treat isn't causing them issues.
If your puppy doesn't take your treats, it is likely that they are a little bit overwhelmed. Try moving them further from the trigger that makes them uncomfortable, and once they are happy and relaxed again, you can try offering them food again. NEVER try to keep them in the scary situation and force your treats on them to get them more comfortable.