Trading with other users on Sweet is an exciting feature to allow you to trade off tokens that you have extras of or aren't interested for others you may like more. Sometimes you may get an offer with multiple tokens for one of yours, or want to offer multiple of yours for one you really want. Some tricks you can use to gauge the weight of a token versus the person offering is:
Token rarity - How many of those tokens were made total? Did the token have a run of just 150 or were there 10,000 of them? Was the token something that was directly available for purchase or as part of a special promo only?
Token availability - Similar to above, another good thing to consider is are the tokens still available for purchase or completely sold out? An older token that is no longer available could have more weight than something that is more recent and can still be bought normally.
Original price - Another simple method to go by is original token price to easily gauge. Three tokens that were $1.99 being offered for a single token that was $5 could be a nice way to "go up" in weight for the $5 token owner by getting more options for future trades and a total higher weight. You can search up tokens on https://sweet.io/ to find out their total run and price - for example below. The token had an original price of $4.99, a run of 2,000 total and they are no longer available for purchase as the availability is zero. Once availability is gone they can only be obtained via trades:
Ultimately it comes down to other things as well such as if you or the other party likes the token being traded for (for example some people may want a cute Robodog so much that they offer multiple other higher weight tokens for one. Making exciting trades to diversify your wallet is just one of the many ways to enjoy Sweet! Check here as well for more info on token rarity.