Like @Lady_Eva recommended she wrote on this a while ago.
I can offer a little more input but yes visualizing a shield and feeling the energy of that shield as a barrier to negative energy. ( remember visualization without energy is just smoke and mirrors, your visualized constructs need energy to back it up )
You can also use this very simple protection spell:
A drop of your blood here would be ideal but not at all necessary
And some herbs: pick and choose from this list but have at least 3, Rosemary, Sage, Thyme, Clove, Cumin.
Mix these ingredients together and keep adding more charcoal till your get your mixture as close to the color black as possible.
Now this is already in itself black salt which can be used for protection by sprinkling in corners which you feel negative energy but you can take this a step further.
Cleanse your house prior to his however way you best can, salt and water, saging it, it only needs to be simple. The aim of this is trying to get whatever negative energy that’s already in to go out.
The aim of this spell as a whole is to make sure the negative energy stays out and whatever remains is absorbed and nullified by your black salt.
Now salt traps negative energy and black as a color absorbs light, it absorbs energy into it. The color enhances the efficacy of the salt.
Once you’ve made and ground the mix the best way you can. Consecrate this to a spirit of your choice who deals with protection: could be angel Michael, could be Hestia goddess of the home, could be Isis, it could even be to your own godself if you’re well familiar with it.
Hold your hand over the salt and feel the energy of your mix, see and visualize energy stream from your outstretched palm into it and will this energy to activate the protective properties of all the ingredients in your mix.
Here you can add a verbal charge to the herb ( by all means tweak or this chant however you wish ):
“Salt cleanse and render anew
Black absorb the malice and hate
Let this House be cleansed by sage
Rosemary chase evil at all corners
By thyme, cumin and clove
Let this negative energy be gone from my home
In nomine sanguinis ( if you added blood this basically calls upon the power of your blood )
Take this mix and go around your property three times sprinkling this around the corners of your home especially where you feel the negative energy is gathered.
As you do visualize and push energy into placing wards that are fortified by your mixture which adds energy and power to your visualizations and acts as a physical marking for your wards so you remember where you placed them when you feel like renewing them.
However you want to visualize this ward is up to you. @Lady_Eva has an excellent tutorial on warding, you can use that.
Don’t hesitate to message me if you need further help.