Bathing, tilaka, acaman
As Srila Prabhupada always said: cleanliness is next to godliness.
If you want to start performing worshipping at home it is very important to be very clean on a bodily platform as well. First goes bathing, then tilakas and acaman. All three are helping you to become completely clean.
Any spiritual activity (chanting japa, etc.) only if you are clean and at least made the environment of you conscious sattvic (in a mood of goodness).
It is recommended to bath twice a day: after waking up and at night, before going to sleep. The morning bath, after sleeping, is mandatory.
First you should brush your teeth and hair (if you have long ones) and make any hair-do that you plan to. After that you can use the restroom and then take a bathe. The option of first bathing and then going to the bathroom, is compared by Srila Prabhupada to the behaviour of an elephant, which first cleans itself in a lake and then puts dirt on its body. A shower is more preferable than a bath.
During the bath use soap and water, and it is very good to use the restroom and the shower in a gamca (a cloth that is covering your waist if you are a prabhu, or body if you are a mataji) as a way to show respect to the demigod of water (avoid being nude in front of him). Before starting bathing you can also chant three times ‘Gange!’ to request Srimati Ganga Devi to be present in the running water.
While bathing, remember than any remaining dirt/bodily products have to be cleaned. Full bath is described onwards. Always clean your eyes, nostrils, ears, mouth (rinse it at least 3 times), arms, body, legs, feet and below-waist areas. To have a full bath means to wash yourself from head to toes, for males it is an everyday standard, for females (if they/or males have long hairs) once in 3-4 days or 7 days. Women also take a full bath (with washing hair) to complete their monthly period (after 72 hours after beginning or when it ends).
Any time bowel movement happens or if you have slept for more than 30 minutes during the day (after waking up in the morning), or if you had a sexual intercourse, this kind of a bath as described above is required. If it is only the passing of urine, then short bath will suffice. It is described below.
Short bath: rising the bodily area with water (if it was using the restroom); rinsing mouth (at least 3 times), washing hands with soap, washing/sprinkling feet & you can rinse your eyes, nostrils, ears. Then sprinkle your had three times with some water while chanting ‘Sri Vishnu’ three times.
REMEMBER! After eating (taking prasadam) you should always wash hands, rinse your mouth, sprinkle your feet and your head with water.
To come near Deities the full bath is usually required. At least, the full bath has to be done after waking up in the morning and then the short bath will suffice. You apply the tilakas on your body after the bath took place. The information is provided below.
It is recommended to be dressed only in clean and if possible vaishnava clothes for service. Cotton and synthetic fabric stays clean only 1 day when it is worn, and silk stays clean for 7 days (from the day of first use). Anything that is unclean or was used should be first washed with water and washing powder/detergent/soap. If you have visited the bathroom in clothes, or you have eaten in them with piece of food falling on your clothes, or had a sexual intercourse, the clothes become unclean and cannot be used for worship. The eating part is less criminal, so just do the short bath, an acaman, at least. The separate special clothes for worship are recommended if you have Sri Sri Radha-Krishna Deities, Sri Silagram Sila or Sri Nrsimhadev Deity.
It is the next step after the bath to make yourself clean and to mark the temple of God, your body, with His names. It is done before putting clothes on, usually in a clean dry gamca (not the one that was used for bathroom).
Use the Gopi-chandan Tilak (or other). Put a few drops of clean water on your left palm and then use the piece of Gopi Chandan to make a paste by rubbing it against your palm. You need to make smooth paste: not too watery, not too dense. Then with the right hand apply tilakas in the following order while chanting each mantra as soon as the finger touches skin. It is recommended to apply tilakas with the right finger of your right hand, never use the index finger or your nails to adjust tilaka, instead you can use q-tips or a piece of cloth. Wooden/metal stamps for tilaka are useful for making beautiful tilaka both on the forehead and the body. If there is any problem with the place where you will have to go later (example, to work), then you can apply tilakas with water (or the one on forehead with water, and remaining ones with chandan, paste). Remember, you are putting on the tilakas not for others to see them (even though it is a very good form of preaching to non-devotees), but for your own good first of all.
Acaman is performed after the morning bath and putting on tilaka, or when you want to begin worship/used bathroom/have eaten. It is just a good thing to clean yourself fully.
You can read more about acaman here, and below you can watch a video with all instructions and more inspiring information! (Kindly note that even though the bramhanical thread is mentioned there, if you do not have a second initiation, you do not need it for acaman).
At 4:09 of the video you will see how to invite Srimati Ganga and all saintly rivers to the water of your acaman water.