Each temple has their own ritual.
I have a ritual here I wrote because I'm not in a temple: http://www.asetnet.net/dailyrite.html
Akhet Hethert has their own ritual in Kerry Wisner's book Eye of the Sun.
The Egyptian Prayerbook has the Senut, the ritual written by Rev. Tamara Siuda of the House of Netjer.
Honestly, the minimum, is purity, a lit candle, incense and a water libation. And then offerings for the particular deity you are worshipping.
Now if you just want to pray, pray. Just talk to Netjer. It doesn't matter where or when. God or Goddess can here you where ever you go and in whatever language you speak.
Personally I do the Senut rite as already said by luellon there... but I also agree that any time anywhere, if you want to talk to Netjer, just do it, just pray, and that can be as regular as you want it to be :)
I pray a lot. Spirituality has always been important to me even before the Kemetic gods came into my life. So just talking to the Netjeru doesn't phase me.
I second the prayer. I also recommend giving offerings, depending on the deity's known tastes - food, flowers, or for those who wish to take it further, a small offering of blood (just a couple pricks with a lancet should do it). You'll get a feeling of whether the offering's accepted, for example, if it's food, it'll taste better. If it's not accepted, you'll get the sense of "Try better." Giving to the gods shows commitment on your behalf and brings about their respect.
I would caution against using the blood.
For the Netjeru blood is taboo and for ritual is considered impure. I would also caution against offering that to Sekhmet especially.
This of course depends upon how you view or uphold the purity requirements the ancients did.
For example I have a friend who has made a ritual so that a menstruating woman can still to a slightly modified form of the ritual.
Hmm. That's interesting because I've heard it as a recommendation and offered it to Osiris before (no adverse consequence, it seems certain circumstances bent backward for me to get home safely that night too...). Then again though, I have limited experience, so feel free to put in two cents wherever.
It may depend of course on the situation in question, but and I may be misreading you, but it doesn't sound like you were in a ritual context at the time.
It may be an okay offering other times, but that may depend on the devotee and the deity in question.
I definitely agree not offering blood to Sekhmet, the only ritual that ever involved blood-offering to Osiris was actually a significant one in my life... but then, it wasn't traditional Senut.
In all other cases (most of which were prayer), I've offered flowers or certain incense, depending on the deity.
The standard appears to be purity with a natron bath and offerings, but I have read where worshipers just offer candy or something to a Netjer "on-the-go" so to speak, without doing any of the purity rituals. It worked out fine with them but it just depends what your relationship is like with the Netjeru.
From my personal experience, some Netjer are less strict then others, as in they are fine with you messing up or not doing the rites correctly, the others will tell you to get more practice.
As long as you mean well the Netjeru will usually accept any offering (except the taboo ones) or prayers.
These sites are usually correct on what the Netjeru like in terms of offerings. http://www.wepwawet.org/wiki/index.php?title=Main_Pagehttp://www.asetnet.net/listofo.html
My regular worship is very simple, mostly consisting of prayer, especially spontaneous prayer. When I have more time to I do henu at my alter, make minor offerings of food and water, light candles and burn incense and bath before hand (scent was connected to holiness by the Egyptians). I rarely have the time to do full rituals or the finances for the offerings I would really like to give. Purity is essential in a full and true ritual though, no ifs, ands, or butts, except the shaving body hair thing, which from what I understand was a cleanliness issue (lice and mites) that we no longer deal with, though it depends on your particular relationship with the gods. I personally find its better to do as many little things as possible and try to cultivate piety and humbleness on a daily basis.
I really like the Henu positions, Henu keeps me humble in my approach to the netjeru and not to lax. There are 3 henu positions, which are all commonly seen in Egyptian art.
1. Henu where you stand, hold your hands up to the Netjer. The hands are about head height, parallel to your shoulders, with palms forward.
2. Full Henu comes in two forms from what I have read; the first is where you perform the henu gesture but drop down on one knee. You can also totally get down on your knees and then touch your head to the ground afterwards.
3. Jubilation henu is when you drop down to one knee and take one fist and stick it to your chest and take the other arm bend it in the air at a 90 degree angle with a fist. You can also beat your chest slowly by switching arms, signifying either mourning or a sense of unworthiness or happiness depending on the author.