There are many different ways you can do this without breaking the bank; window treatments, decor and bedding.
For window treatments, it's important that there is some way for guests to control how much light comes into the room while not making it too dark or difficult for sleeping if needed later on in the day; think about where sunlight may come from (i.e., around mid-day). A great option would be blinds because they're relatively low cost and easy to maintain. Day and night roller blinds in Sydney homes are a very popular choice because they provide just the right amount of control over light and privacy. Another popular option are roman blinds in Sydney. Curtains would also be a good idea, but there are a few things to consider here, such as the opening and closing of them as well as any materials they're made from (i.e., if it's too noisy or slippery, guests may have trouble with this).
Guest bedding is another important consideration because you want your guests to feel comfortable when sleeping during their stay. They ned to be attractive yet cosy and comfortable. The other aspect of bedding is that they need to be easy to clean; guests are not used to sleeping in your bed, after all. You should avoid heavier bedding when it's warm outside because this could make people feel too sleepy or even sweaty at night.
The decor in your guest bedroom is also important to consider. If your guests are coming in the summer, they will want light colours and breezy fabrics that look good under the heat of a hot sun; you can also add some pops of colour here and there to make it more interesting. If your guest bedroom is used more during winter months, then darker colours might be better for decorating since there won't be any direct sunlight streaming into the room anyway. Warm tones work well with cosy textures like soft wool blankets or down comforters along with plush pillows on hardwood furniture pieces rather than fabric upholstery which tends to absorb dust easily if not vacuumed regularly. Large floor rugs make a room look very cosy and inviting too.