It's not vital to have a professional looking dojo at home in order to train. The important thing is having a comfortable place to train that is readily accessible to you. During nice weather this can be as simple as stepping out into your yard. If you want a more developed home dojo here are some things to think about.
The floor. This is often overlooked, but think about it. You're walking around barefoot, sitting on the floor, and sometimes kneeling during training. If the floor is too rough you will be risking injury and at the very least shredding your gi. Some things to consider when choosing flooring wold be a very thin carpet, or jigsaw floor matting.
Targets. While practicing your techniques on the air can be extremely valuable, it's also important to develop striking power by actually hitting a target. There are a few to choose from and I'll write some of the benefits of each. A standing heavybag is good for powerful striking and it's portable since once you drain the water, they're quite light. A hanging heavybag is good because it moves as you strike it much like an actual opponent. The drawback to a hanging heavybag is that it has to be integrated into your ceiling which can be disruptive.
Space. You will need enough room to train effectively. If you're always half worried about bumping into a wall, focus will be difficult to develop.