The best advice that I can give you, consider doing things that are an investment for yourself and not the landlord. What I mean, is think about doing things that you can take with you and use again. Here are a few ideas:

1). Area rugs on floors. For an inexpensive area rug- You can order wall to wall carpeting and have it cut into any size or shape and then have the edges either bound or serge. Good way to cover an ugly floor and bring in colors that you like. Better yet, find an old weathered torn edge rug at garage sales or flee market and have the edge bound or serge, as well as cleaning the rug will make it look brand new area rug.

2). Artwork- Take photos of flowers, landscape, people, buildings or pets and then frame them. Look for greeting cards and frame them individually or in a grouping (See Photo # 1) You can find interesting things for your walls at flee markets, garage sales, vintage stores, etc. Have your children paint some picture and frame them. I have got to say, they make the best contemporary artwork! Mix their painting with a photos of them next to it.

3). Window Treatments- Buy spring tension rods (even shower curtain rods can work for larger window), use as an inside mount. Hang window treatments from them. There is no need for holes or damage to the walls when you leave.

4). Bathrooms, kitchen or any floor area- Order floating floors that can lay over top of the existing floor. You can take it with you when you move. After all, this is what they do in Europe. There are several options to choose from like laminate floor, engineer wood floors, cork plank flooring in PHOTO # 2 ..........OR WHAT ABOUT THESE IDEAS?

A). Design Material - http://www.dmikc.com/catalog_new/products.php/?cid=124 / Their Tuuli Flooring /style Season's or Rumba vinyl sisal looking floors. It is a thick textured vinyl that looks like carpet (wall to wall) sold in 6'-8" wide and any length. You can cut to the size like a bathroom floor, for instance. It lays over top of old existing floor, NO GLUE is needed, you just lay it over top of old floor, cut around toilet with slit at back on toilet. Easy to do it yourself and take with you. (See PHOTO # 3.)

B). Karndean International Flooring- Loose Lay wood planks or tiles. Again NO GLUE! You just butt them together tight laying it over the old floor and take it with you when you leave. See PHOTO # 3
http://www.karndean.com/en/commercial-flooring/range-overview/karndean-looselay.aspx?link=cta

5). Kitchen Backsplash-

A). Order resin panels from Lumicor or 3Form which are two translucent panels with material flatten in between them, like leaves, grasses, rice paper, fabrics, metals, etc. Take the panels and cut to size of back splash and hold in place with molding/ trim. Easy to remove and take with you when you leave.

B). Purchase wonder board/ cement board from local hardware store. Cut the cement board into the size of your backsplash, then tile over the top of cement board and then grout it. Lean up against walls and hold them on with wood moldings or purchase picture putty that is strong enough to hold them to the wall without damaging the wall. Check with your local hardware store for the best one to use. You can take with you when you leave and doesn't hurt the walls. Look for coaster and use as the deco tiles. (See Photo # 4). The chef deco tiles are coasters that were found in a kitchen supply store, four of them for $ 8.00.

6). Find old furniture, like dressers or coffee table, paint them. Sometimes leaving the top wood if it is in good shape and just paint the legs or visa-versa can give the piece a whole new look for not much money.

Really there are so many things you can do. Be creative and think out of the box!