First of all, it's very important that you check what your lease says and/or what your landlord's policy is regarding what you are permitted to do in your space.
Some will be more relaxed than others, but don't be surprised if you are required to leave the property in its original condition when you move out.
Textiles are the easiest little tweak in the book. They give a space so much personality, without having to make any drastic changes. I recommend starting with a rug. Although rugs are often on the expensive side, they'll make the biggest improvement to your space, particularly if you're dealing with some not-so-nice flooring or ugly carpet.
A nice big jute rug is a great way to create a minimalist and modern feel — choose one that goes from wall to wall for a new-carpet look without the cost or hassle.
Next, choose some smaller textiles like cushions, throws and curtains to top off your colour or decor scheme.
Updated curtains can also completely transform a space.
You're probably not going to want to get an electrician in to change the lighting in a rental, so you're going to have to work with what you've got. However, there are plenty of options for personalising the lighting. Use oversized pendant lights and lampshades to add a feature to a room. If you're dealing with poorly-placed lights or bad bulbs, add some lamps to give the space a warm feel.
Shelves are the perfect way to create a space that feels uniquely yours, and there are lots of options for integrating shelves into rental spaces.
Floating shelves are lovely, but you may not be allowed to mess with the walls. If you are allowed to add the odd nail to the wall (ask first!), hanging leather shelves have less impact on the wall than floating shelves, only requiring two small nails. Otherwise, use shelves that stand on the floor, like simple rectangular shelving or some shelves made from a ladder.
To me, a house isn't a home without indoor plants. And if your rental doesn't have outdoor space, you're going to want to bring the outdoors in. Hanging plants, big feature potted plants and smaller plants all add interest to your home without risking your bond. They also do a great job of disguising ugly walls and floors.
Baskets are another decor item that adds texture to your space without too much colour or distraction. They're great for storage, making them functional as well as pretty. Baskets are perfect in spaces like the kitchen and laundry that require lots of different ways to store (aka cover up) items like food supplies and clothing, and they also make great planters.
Art is often the cherry on top when it comes to interior design, and even one or two inexpensive pieces can breathe life and uniqueness into a space. It can be a challenge to hang art in a rental space if you aren't permitted to nail anything into the walls, but there are lots of options for displaying your art — place it on top of a cabinet or on a shelf, or lean larger pieces against a wall. There are also other options for hanging it — for lighter pieces, use 3M Command products that don't leave a mark, or use Blu Tack to hang posters.
I've often found that rental homes could do with having a wall taken out to really open up a space, but that's not likely to happen. One way to open up rooms without the huge expense of demolition is to lean some big mirrors against the walls. They don't need to be expensive. Look for large ones that really do feel as if you've inserted a door in the wall.
If you're looking to take the upgrades a little bit further, painting is a great way to make a big change without knocking out a wall. Simply ask your landlord what they think, and know that often you will have to revert the space to original condition when you leave. Wall decals can be used to create the same effect. Another idea is to swap the knobs and hardware in the kitchen and bathroom.
