Hints

• While you have to build every house in the game at least once (There is no way around it. If, in a game against opponents, you capture a factory you do not yet have, you can build the houses that use this resource, but you do not get access to the tenants of this level, even if you can breed them), but you do not have to keep them. You just have to have all three of them at a given moment; then you can sell them if you want.
• You can sell every house (tenant houses, not resources, utilities, and undesirables) as soon as it is built at a healthy profit, so don't hesitate to experiment. Selling the house may also be the best solution when you are confronted with a tenant complaint you cannot fulfill.
• For every level there are two types of tenants, rent-payers and breeders. Not only is the rent-payers' rent higher, so is their life expectancy. Especially in the higher levels it is a good idea not to rent to breeders at all.
• While tenants reproduce only in buildings of their level, sometimes lower-class tenants will pay a higher rent. This is especially true for the students (hippies) who will pay the highest rent in any building up to Mock Tudor.
• Hippies (students) and nerds are the only tenants that require a special kind of fence. Hippies want country hedgerow, nerds white picket. The major, on the other hand, dislikes the solid brick wall, dry stone wall, and railings.
• Keeping up with the Joneses is very important for your tenants (at least those from level 3 up), if they see something in their neighbors' garden, they want it too. So never put Professors on the same block with other tenants, or you'll have to give them all garden sheds.
• Tenants tend to demand gadgets when they are generally unhappy with something. You will often get seemingly unrelated complaints from neighbors if a house is vacant for a while: living next to a vacant house will reduce tenant happiness by 5%.
• An empty building will get infested even when properly maintained. A mouse trap prevents that, but cannot be installed in an empty building: like all the interior gadgets, it has to be fetched by the tenant.
• Wrongly placed outside gadgets can be blown up by a foreman.

How to Keep Them Happy

• Give them big gardens. The size of the garden is really the most important key to tenant happiness. I could not yet calculate an exact ratio, but as a rule of thumb every additional garden tile will add 1/3–1/2% happiness.
• Give them trees. Even if they seem not to care about them (Punks, Nerds and Stockbrokers will never demand trees) the first tree raises their happiness by 10%.
• Upgrade their rooms. Upgrading fom first to second level will raise happiness by 10%, the next two levels 5% each.
• Give them houses above their station. Unless you want them to breed, there is no need to match the level of the house with the level of the tenant. In many cases lower level tenants will even pay a higher rent.
• Give your level 1 and 2 tenants garden gnomes. They are hideous, but will raise their happiness by 10% (possibly only 9% for level 2 tenants).
• Avoid making them share the estate with a factory of any kind. The council demands you have one house for tenants on each estate, it does not require you to actually put tenants in. A resource that is manned will reduce the happiness of tenants by 18%, the Gadget Factory will do the same when it is actually producing. This effect is cumulative.
• Make sure everything is completed before they move in, and keep the house in good repair.