How to improve the look of skirting board in tenement flat?
You're renting, so...
Get it in writing from the landlord that it's OK to make permanent changes like this. Otherwise you risk losing your damage deposit. Yeah, even though you're making it better, some may get picky. Better safe than sorry. Oh, did I mention get it in writing?


To spiff up the existing trim:

Use some sandpaper on a sanding block (a fancy store-bought one, or just a block of wood) to sand down the lumps &amp; bumps.
Use the sandpaper free-hand to sand the paint off the surface of the dips. You may need to dig into some dips with the paper wrapped around your finger tip. You'll want to get as much paint off as possible for the next step.
Fill in the dips with some wood putty, then sand the surface flush and smooth when it's dry.


Apply the molding:

That pine molding is called &quot;quarter round&quot; and this is a perfect application for it!
The nice straight quarter round may show dips and bumps in the floor or wall. If it does, and you want to go to the extra effort, cut back the quarter round to go around the bumps and to fill in the dips
Use small diameter finishing nails (they have a very small head) to nail the quarter round in place. You'll want the nails to be about twice as long as the quarter round is deep. If you want to do a really good job, get a nail set and some wood filler.
Use the nail set to drive the head of the nail just below the surface of the wood.
Use a dab of putty to fill in the resulting hole.
Sand the putty smooth once it's dry.


Paint it:

You should be able to use any latex paint to cover the whole thing up.
If you're getting fancy, you could scrape up a chip of paint and your local paint store should be able to computer match the color exactly.
Sand the edges of any paint chips, filled dips, etc so there is a nice smooth feather from the painted to unpainted wood. Any edge will be magnified when you're done painting.
Put a line of masking tape on the floor next to the quarter round. Put another line of tape against that one, holding down some newspaper/drop cloth/whatever to protect the floor from accidental drips.