Bhagavat vigraha AarAdhanam (Salagram Seva pujan) is not as simple as one may think. It should be done as per the Aagama (PAncharAtra or VaikhAnasam).
These two Aagamas must not be mixed. If you belong to pAncharAtra school (Sri Vaishnava, Brahma-Madhwa Vaishnava, Gaudiya Vaishnava), then, you must have pancha-samskAram to do AarAdhanam (worship). If the vigrahams were of vaikhAnasa worship, then the person must be born in vaikhAnasa tradition to do AarAdhanam of VaikhAnasa pratishTA.
The SAlagrAma mUrti must be daily worshipped by a person who has undergone pancha-samskAram (SamASrayaNam under a SrI VaishNava AachArya) (Pancharatrik diksha). The AarAdana kramam as prescribed by SrI VaishNava Aagama SAstrAs (VaikhAnasam or pAncharAtram) is to be employed in AarAdhanam with prescribed purity. If the person is not able to do AarAdhanam daily, he can offer milk or cooked-rice with ghee to perumAL using SrImath ashTAksharam and dwayam and prostrate before the mUrti. On week-ends/holidays, he can do AarAdhanam in detail. If the person is not able to do even that simple AarAdhanam, then he can offer pure water daily to the mUrti. Even if that is not possible, then the person has to shed tears of sorrow considering his own incapacity or lack-of-interest or lowkika-interest. What else is more bad in terms of "effect" than this?
There are number of ways to perform AarAdhanam for SaaLagrAmams at one's home:
1) Taantric way with ShOdasOpachArams (16 upacharas).
2) Standard Bhagavath AarAdhanam followed by VaishNava Dinacharya established by AchArya RaamAnujA (please refer to AchArya RaamAnujA interactive multimedia CD ROM for details or ask for help from the family elders or AchAryAs).
3) Chathurvimsathi Murthi sthOthra KaTana PoojA This is simpler and any one can do it by reciting this sthOthram in front of SaaLagrAmam(s) and offer Pushpam, Milk and NaivEdhyam. Thirumanjanam can be done with few spoons of milk as well.
4) Those who are in a hurry can take few minutes to recite the two dhyAna slokams, perform japam of AshtAksharam, offer milk, Taambhulam, Karpoora haratthi. The SaaLagrama Moorthys at home should NOT be neglected and starved since inauspiciousness will result otherwise to the home.
The two dhyAna slOkams are:
dhyAyAmi Devam Lakshmisam Shankha-chakra-gadhAdharam
PeethAmBara paridhAnam Padhmasannibha lochanam
Mandasmitha mukhAmbhojam madhanAyutha Sundaram
MaayAnirmitha lokaougam megasyAmala vigraham
Sri LakshmI NaarAyaNam dhyAyAmi
NamO NamasthE KaruNAlaya NamO NamasthE KamalAdhavAya
NamO NamasthE JagathAm cha srashtrE namO namasthE nathsOka harthrE
ThrAhi maam KaruNAsindhO ! Paahi maam KamalApathE!
Thvayi bhakthi: sadhaivAsthu mama sarvArTadhAyini
(Om) NamO NaarAyaNa ….Subhamasthu.
Even on days in which one is unable to perform AarAdhanam for SaaLagrAma Moorthys, The ladies of the house or children can recite the above slOkAs in front of the Moorthys, offer the food cooked for the day as naivEdhyam and complete the aarAdhanam (puja) this way.
SaaLagrAma dhyAnam (meditation) is one of the most auspicious dhAnam.