Hanging pictures on the wall is reasonable, but you should discuss this with the landlord because one of the most common issues at the end of a lease is the holes in walls which stand out, or the tenant’s plaster job to fill a hole.
Some people have created holes in a crude way which starts a crack or makes a big chip, such as trying to hammer a nail of some size into a cement wall. It’s a simple matter to bring in somebody with a proper drill and the right sort of bit to make all the holes you need and which are of an appropriate size, as well as mounting items. Many landlords are willing to send in their own technician who they have confidence in, whereby the tenant can get all the holes they want.
When moving out, I suggest you talk with the landlord first about whether it is expected that you will plaster the holes closed and touch up the paint. The landlord may just offer the same holes to the next tenant and plaster and touch up those they don’t want. Depending on how long you stay, the place may need repainting anyway.
Some buildings have a policy of a 100 baht charge per neat hole, though some have a much higher figure per hole.
Holes in walls have been one of the things which stand out during a walkthru after the tenant has vacated and in the list of damages which some landlords may want to deduct costs from the deposit. Therefore, we try to deal with these issues in advance of signing the lease.