If you don’t know much about the God you want to worship, start with research, read and learn about them more. (Always a good place to study about the Netjeru is Henadology website.)  

After learning more about the Deity, you can start worship. It’s not required to do any formal rituals of “introducing yourself”, however there are examples of such rituals if you feel so inclined.
You may start simply with a short prayer and offering. Or just with prayer, as prayers always is more important than material offerings.  
You may start offerings with candles and incense, later offer something edible. It’s never wrong to offer Netjeru water, bread, fruits and sweets.
Kemetic offerings are usually “reverted” after some time of being presented to the Netjeru. So, offer the things you will like to consume yourself, later!
 
And if you already reached the God/s and established the devotional relationship - then work on this devotion more than on the offerings.
Show them your love. Think about them. Repeat their names in your mind. Say them praise. Study about them. Use the opportunities to see more of their pictures and read more about their mythology, cult, ways of worship. Contact other devotees of that God and see their experiences.
But before all, IMHO, is thinking about the God/s, keeping them in your mind, let them make a shrine in your heart.

They welcome our love and devotion more than material offerings. Material offerings are more for us than for Them, because they help us to keep our attention focused and concentrated.
The same thing is with holy images and statues. You may look at the pictures of the God on line, you may make a home shrine, but most important is to welcome them into your life and your heart.

Because what else was your goal in connecting to individual God?
You want to be their friend, perhaps. And yes, this means that they would influence your life. This does not happen in one moment. But you may find eventually that you start changing “in the likeness of the God”. Their values become your values. Their goals and agendas become yours. You start to love what they love, and reject what they reject. You think about them more and more, you wake up with first thought of saying hello to the God.

Deities are not bound by their “main function”. It’s very limited approach. Deity of motherhood is not ALL about motherhood only. Healer deity is not only for the worshipers who are doctors. Gods of War are not only for those who serve the military.

But the more you work together with the God, the more aspects of their personalities you see. Their likes and dislikes. Their highest values and their compromises (for example some of them may be very demanding about regular and formal rituals. Some of them may be absolutely relaxed about it. Some of them may be very specific about favorite offerings. Some will accept tap water and loaf of bread and never ask for anything more, leaving the choices to you. Some of them would like you to study, some of them would challenge you to do the charity work. Some of them may make you more focused on caring about nature and environment, others may inspire you to help people in need, another may push you to focus on self-care. Some may inspire you to make creative work, some will enjoy drawings and poetry, others would prefer music and dance.

Think what drawn you initially to the God, there was a reason to invite Them personally. This reason is valid. And then, if you ARE contacted, research more of who they are. Their epithets and myths help you to understand their personality, their place in the universe, their part of the Great Work.

Small devotional activities help you to keep the everyday practice up. You can also dedicate your daily activities to the God/s. Especially of something is hard to achieve. Connect your life to what they do. Your housekeeping work may become a part of great Keeping The Universe Up and balanced.

And just think about Them. Repeat their names. Look at their images. Bow before the shrine. Say the short prayers on every occasion when you feel like it.
You don’t need a special time a place for worship and devotion. If you are connected with the God, try to realize that They Are In Your Life Now. You live the religion. The most important temple is the one you establish in your heart.

They know everything you do. They are always watching. They know what you post online and which videos you liked on Youtube. They may see the human world through your eyes. Honor Them well! :) and send them your love with every breath and every heartbeat…

Just think of them!
Listen to the songs from your devotional playlist.
Wear the devotional jewelry pieces.
Have the image of Deity with yourself, even if you keep it locked in a bag and can only look at it at night.
Have some devotional texts stored on your phone/tablet/netbook.
Pray in your mind.
Dedicate some of the the activities you can, to Gods (especially maintaining Maat in small ways: helping others, volunteer to do the dishes, whatever :)
Dedicate self-care activities to Gods.
Dedicate to them your studying, reading, writing, music, dance, craft, any other thing you can do...
 
Once you have established a pattern of performing certain devotions daily, that pattern becomes the minimum of what They expect from you. […]
…once you have established a devotional routine for your gods and spirits, Whoever They may be, I would still strongly advise you to stick to that routine. In the end, you will get out of your practice what you put into it, and there is an accumulation of power and of holiness that builds up over time when you perform a ritual activity (no matter how simple it may be) each and every day. It is this accumulation that can see you through the tough times, the times when you can hardly bear to keep going with your practice, when you feel you can barely even do the bare minimum. It is this that will help you keep going.

— (c) Beth Lynch “On daily devotions”

You can indeed worship some of the Gods more intensely and develop close connection with Them… One, two…
But ignoring the rest of the pantheon, a whole family, would not be respectful to Them.
This means: while focusing your worship around chosen deities, don’t forget that there are others, who may one day also make appearance in your life.
Being respectful means not excluding other Gods of the Divine Family from your religious practice, even if you don’t honor them regularly, it’s better to be open for possibilities :)

I personally always wonder when polytheists ask “How can I handle (N) Gods”?
This is polytheism. This is the ultimate essence of the religion: we do have many Gods. The whole pantheons, the divine families.

And They (Gods) are here not to be “handled”.
They are here to help you, guide you, care about you, share their love, wisdom and other gifts. Indeed they may ask for something nice like offerings and devotional actions. And “hire” you for work. :) (not necessarily priesthood)

The Netjeru live on Maat, they know us sometimes better than we know ourselves and they would not bask for *things* we can’t handle.
They know our limits and they know what they can ask from us and what they can give.
Honoring Many Gods doesn’t mean necessarily creating a separate altar/shrine for EACH one, doesn’t mean buying new set of libation and offering dishes for each.
Netjeru, usually, are perfectly okay with sharing spaces, especially of you have a shrine, not a TEMPLE with holy-of-holies, dedicated kar-shrine(naos) room, etc.
They are one big family and usually, in 99% of the cases you can make a combined shrine for many Netjeru at once. And also make separate devotional spaces for the Gods that have greater importance in your devotional life.

But generally, if you join a polytheistic religion, there ARE many Gods. Just get ready for it!
It always confuses me when polytheists only pick one or two deities and say “I worship N and NN, oh why NNN is also coming?”
Because that’s polytheism and they’re all family, that’s why! :)

You can of course have favorites: Deities you are especially & deeply devoted to. Those who are “your first”.
But anyway, “signing” for polytheism, you place the “welcome” banner over your life for the entire pantheon.  

Don’t wonder if they may start knocking your door and come to call you for adventure!