This is a guide to one way to do an Uncrossing bath ritual.
For this ritual you will need
2 small white candles
A bathtub
A mixture for Uncrossing
Water
A cup or small tub
Uncrossing oil

Extras (may not may not be optional)
A cooking pot, medium to large in size

The first step is preparing the bath mixture. If you are using a mix of herbs, such as a 13 herb bath, you will need to steep the herbs, like a tea, and you will also want to strain out the herbs before adding the herb infused water into the bath. A simple muslin sack, or putting the herbs into a cheese cloth and making a sachet with it is quite effective. A medium to large cooking pot can be used to heat the water and steep the herbs.
If you have a different mixture that will quickly dissolve in water, then you can skip this part.

There are many bath mixtures. Some are purely herbs, others might be pure water soluble minerals, like a mixture of salts and soda. Some can be a combination of both. A simple way to make your own is to pick three herbs for Uncrossing, any three, and just use that. Or pick three minerals, or a combination of 3 items.
Here are some suggestions
1) mint, eucalyptus, hyssop
2) Rue, Nettle, Verbena
3) Salt, Epsom Salt, Baking Soda
4) Salt, Epsom Salt, Blueing
5) Hyssop, Pine, Eucalyptus

Draw the water in the bathtub. Use a comfortable temperature. As the water fills in, you should add the bath mixture.
As the bath continues to fill, take your two white candles, and anoint them with Uncrossing oil. Place these candles at opposite ends of the bath, so that you step between them when you get into the bath. Light the candles.

You should have your cup or small tub with you, possibly sitting on the ledge of the tub (away from the candles, but not in your way). Disrobe and get into the bathtub.

Now, while you are in the bathtub, here is a question of what you do. In a Christian tradition, you would recite a prayer related to your work. If you have been cursed, it is common to use Psalm 37. If you are seeking purification, it is common to use Psalm 51. You can also use Psalm 23 for just about any purpose.
If you are not a Christian, what should you use? Well, you can still use the Psalms if you want. If that is really contrary to you, then there are some other options.
If you are familiar with spiritual energy work, there are many practices which involve cleansing your spiritual channels and centers, your aura, etc. You can do that while in the bathtub.

If you are a really old school occultist, this would be the time to attempt the bathing ritual from the Greater Key of Solomon. I am not going to write that all down, when a perfectly good website describes it all, clearly. Just google “Key of Solomon Concerning the baths” and go to the website named Esoteric Archives. If that doesn’t show up in the first page of searches, I don’t know what to tell you.

This is also where you could write your own incantations for curse removal and spiritual cleansing.
An affirming declaration of “I am clean, clear, whole and restored” repeated regularly while sitting in the bath can do the job.
You could also combine all of these methods in any way and get a very good Uncrossing.

When you feel you are finished, take that cup or tub, and take some water from the bathtub. Set it aside, and get out of the tub. Let the water drain away.  Allow yourself to air dry. This can be assisted by going on putting on fresh clean underwear and underclothing. The clothing will absorb the water, and then rapidly dry out from your body heat. You can also turn on a heater or a hair dryer if it’s really cold and you want the extra warmth. If the weather is hot and dry, just stand in front of a fan and you will be dry in no time.

Finish getting dressed in clean, fresh clothing, and then take that cup of water and go outside. Find a large, healthy tree, and while facing East, pour the water out onto the tree. A Christian would “In the name of the Father, Son and Holy Spirit” while doing so. Another person can just say “SO IT IS”. Once you dump the water, turn around and walk away without looking back.
For truly best results, I highly recommend doing the whole bath before sunrise so that when you are dumping the water on the tree, it is sunrise, or shortly thereafter.

You will also get very good results repeating this ritual bath several times. Especially if you have been crossed a long time ago and are finally removing it, or it was a very nasty and fast acting curse. A very bad situation might require a full lunar month of ritual baths, with only short breaks during the full and dark moons.
3 days can be enough for more simple issues like an unexplained streak of bad luck
7 is good if you have strong evidence that someone has cursed/crossed you.

If you want to really commit to doing magic, spells, and rituals, I highly recommend taking up a practice of regular, monthly, Uncrossing ritual baths. I personally did such baths every Saturday for many, many years. It has brought a lot of positive changes in myself and in my life.