Sigils can be quite useful if you do not have an altar and even then you do not have to use them but is rather a choice for that person. If they do feel that using sigils is easier for them, then that is great. The most common thing people do if they do have an altar is that they put pictures of sigils on them which is fine.
It is true that there are people who believe that you need all these fancy ritual items to contact a spirit. Indeed it is a choice to have all these nice ritual items on your altar. Some people want to make it sound that you need all this fancy stuff to contact a spirit which it is pretty ridiculous. Some even just want to make it sound that this path is very difficult when really, it is not a difficult path to follow. It takes time and dedication to educate yourself on what this path is really about.
Meditating and Focusing your mind on the sigil
Meditating and focusing your mind is a great way to stimulate the mind and it can help you concentrate on the sigil of the spirit you are trying to contact. To learn to be able to contact a spirit through meditation is a great start even for a beginner. And even for a beginner it can be difficult but if they do focus on their meditations it can lead them to something much greater.