One of the biggest issues relating to land in Second Life is that of other residents building on your land. If you go away for 4 weeks and leave build turned on, you can bet your land will be full of junk and you may possibly have the odd leecher squatting there as well.
Sadly, many people do just that and it causes grief, upset and distress to neighbours and people who are trying to live around you.
How bad could it be? A plot near me recently had approx 1500 items on that weren’t the owners - things such as plywood boxes, particals, rotating objects, stuff for sale etc. Real sim laggers! No one wants to live near that.

Linden Lab provided all land owners with the tools to actually stop this happening but many land owners don’t actually know how to use these tools.
This is a beginner level article and should be viewed as mandetory, unless your land is a sandbox.

• All controls can be found under the top menu ‘world’ and then ‘About land’.

There are 2 main things you can do about people building on your land. The first is to turn on auto return and the second is to disallow any resident from building.

Auto return:

• world/about land/objects tab

Auto return does just what it says, you enter a number between 0 - 10 in the field provided and any residents objects will be returned after the number you set in minutes. (0 means it wont return and is turned off).

Auto return is useful if you have a store on your land and expect people to unpack boxed items.

Auto return will not return the land owners objects and if you have your land set to a group it will not return group members objects - just anyone elses.

Disallow any resident from building.

• world/about land/options tab

This option is more suitable if you don’t want anyone building on your land at all (except you and your group). All you need to do here is un-tick the box between “Create objects” and “all residents”

Doing this will block peoples ability to build anything on your land. However, some people might build next to your land and then drag objects over to your land. To stop that also un-tick the box between “Object entry” and “All residents”.