Work
"Work" is where a player must do physical or mental tasks, in order for the game to function.
Work is bad
Keep it to a minimum.
Work that's a regular part of the game turn, is a huge negative. You should consider changing your game significantly, to remove such work. It is not a minor matter.
It's also very easy to forget to do the work, and have to fix up the game.
If you have to choose, it's better to have rules clunkiness or complexity, than work.
Setup
Your game should have minimal setup and teardown.
While pre-game work is better than in-game work, onerous pre-game work is too often excused.
I've seen numerous positive mentions of Radlands having almost no setup. You just shuffle and begin. It's really nice.
Avoid designing games where all the pieces must be placed on the board to begin with.
Some games are adjusted for different player counts, by forcing the players to go through each deck, and remove certain cards.
When you play Bärenpark with less than four players, it tells you to remove some combination of tiles from each of the piles of tiles numbered 1-7. Do I really have to do that? Would the game be terrible if there were just too many of those tiles? This is in addition to having to arrange all the game's components on the board to begin with.
Avoid having the players count out some number of cards before the game. Even more so, don't make me put cards "15 cards from the bottom", or do other complex deck stratification. Far worse, don't make me go through the deck and add or remove specific cards. Please let me just put the deck on the table, and start playing, even if the game won't be perfect.
Moving things
Avoid placing game components on the board, only to remove them from the board.
In Agricola, resources are placed on the board, and players can take them. It's a key part of the gameplay that untaken resources will build up over time. The problem is that each round must begin with adding resources to the board spaces. A Feast For Odin, a related game from the same designer, has board spaces that mostly just tell the player to get resources from the supply.
The same goes for cards, though there can be reasons to have a "card market" of visible cards. Avoid card rows that you need to replenish every time a card is taken. Maybe a player can pay to replenish the row in one action. Especially, avoid card rows that slide along.
Mathematics
Keep numbers as small as possible. Not everyone is good at mathematics. I can total five dice, or add 16 and 27, instantly. Many people can't, and I would still rather not have to.
Halve all the numbers in your game. Does it still work properly? Good. Keep going. You might like the exact ratio of the buildings worth two and seven points, but just make them one and three points, please.
Something in your game should be worth one point. If that's not the case, your point values are too high.
Yes, it's nice to find an exact mathematical equation that matches your design objectives, but players don't want to do mathematics.
Use maximums and minimums only when necessary. The same goes for addition and subtraction ("the number of soldiers you have plus two"). People can double or triple numbers, but avoid making players halve them. This simple mathematics isn't too much extra work, but it should still be avoided. It's more of a kludgy design choice, and slightly immersion-breaking.
Ideally, things are one-for-one.
All of this is better than points tables, where you look up how many points 3 cows is worth.
Scoring
Does your game have to have "point salad", where everything is worth points?
Most things should be worth zero points.
If you just print points values on things that are worth points, and there's no mathematics or tables, players can just add up their pieces. If you can't print point values on your objects, just make a few valuable-seeming ones be worth points.
Don't make the players get out a pad at the end of the game, to add up.
Counting
Try not to make exact high numbers matter.
Many players can't count things easily.
In Race for the Galaxy, players must discard down to ten cards in hand at the end of each of their turns. That means every large hand of cards needs to be constantly counted.
Magic's Odyssey expansion introduced the "threshold" mechanic. While seven or more cards are in your discard pile, some bonus effect occurs. This requires that players constantly tally the number of cards in their discard piles.
A better way to do this is to make the number only be counted at certain points, or when certain things happen.
In Catan, whenever any player rolls a 7, all players with more than seven cards discard half their cards. This is much less work than forcing players to discard down to seven cards at the end of every turn.
Memory issues
Memory issues are where a player must remember something. This might be in order to make the game function properly, but is usually just advantageous information that the player should keep a mental note of.
"Look at a player's hand. They discard a card of your choice." That's a decent ability, but the player really should take note of all their opponent's other cards, and keep them in mind. That's not fun, but you're a bad player if you don't.
In Splendor, players can reserve cards from the table, to buy later. However, when they do, they turn the card face down. Players should take note of this likely-important card, but that's mentally taxing, so they don't. Later, the player plays the card, and wins.
I don't like to have to keep something in mind. I just want to think about my strategy. If there's something that people have to be forced to remember, get rid of it. Alternatively, make it something good, that they'll want to remember. Or, make it something big, that they'd notice if they forgot. Or, use a physical component or cue to remind you.
Some games are about memory. That's fine, but most people don't really like memory games.
Once information has been made public, try to keep it public, or throw it away.
Observation
A player must be observant, to make sure a condition is or isn't being met, or must constantly evaluate known information, such as how much money each opponent has.
The game Dead of Winter contains "crossroad" cards. The player who draws it keeps it secret, and when the secret condition on the card is met, the player reveals the card, and something happens. People like these, but they generate an ongoing and distracting observation task for the players, and a high potential for mistakes.
Referring
Don't make the players look up data. Everything in the game should be memorisable. This includes the game setup.
Cards with text should be self-explanatory. If a normal person will read the card, and need to check the FAQ, the card needs to be rewritten.
Add a reward
If players can get an immediate benefit from doing work, they'll be less likely to feel bad about it, or forget to do it.
In my pirate game, at the end of each player's turn, they had to roll the die, and do some maintenance. This was a drag. I moved the roll to the start of the turn, and made the die mostly give the player movement, and only occasionally do some maintenance. Players were excited to roll the die, and didn't forget.