Please how are we to sex our wives in accordance to the SUNNAH?
And is it permissible to suck(her breasts) and finger (touch her sexual organ to stimulate her)?
BISMILLAH This is a very important topic in our lives as Muslims but unfortunately most of our scholars and alims fail to talk about it due to shyness or it's sensitivity. It's not something to be talked about in the mosque with a microphone so you barely hear our preachers talking about it. To answer this question, I will first get some points clear and then provide Hadiths and ayahs to back it later on.It's very important to get your wife aroused before penetration that's what's called pre-intimacy because the prophet had talked about it.
So this is where caressing, kissing, the sucking of nipples and fingering comes in.
Anal sex. Is highly forbidden in Islam Period

MouthAction is undesired and disliked but not haram. Health-wise, MouthAction could be dangerous sometimes. Women have active and unharmful vaginal bacterial and natural PH(potency of hydrogen) within their genitals which makes it not sound for that place to be licked by the tongue or mouth. This varies from woman to woman regarding the nature and hygiene level. However, the clitoris could be carefully licked by the tongue but this should be done right after bath and not to be done deeply but don't forget that it is highly disliked and undesired by some scholars though there are other views that supports and allows that so opinions vary on this matter.
Felacio/MouthAction or the sucking of the male genital organ by the woman is also considered to be unharmful by medical practitioners and acceptable in Islam although opinions vary with regards to this.
Bathing and being clean is thefirst thing to consider before carrying on with it.So with this, individual desires, conditions,hygiene and personal health conditions counts. Intercourse during menses is very bad and haram to the highest level.
Yes, sexual positions are allowed so far asits in the right place (vagina).
You can try doggy style, spooning and the others if you like instead of sticking to the well known missionary position.

Now let's talk about pre-intimacy Imam al-Daylami (Allah have mercy on him)records a narration on the authority of Anas ibnMalik (Allah be pleased with him) that the messenger of Allah (Allah bless him & give him peace ) is reported to have said: “One of you should not fulfil one’s (sexual) need from one's wife like an animal, rather there should be between them pre-intimacy of kissing and words .” (Musnad al-Firdaws Of al-Daylami, 2/55)Imam Ibn al-Qayyim (Allah have mercy on him)reports in his famous “Tibb al-Nabawi” that the messenger of Allah (Allah bless him & give himpeace) forbade from engaging in sexual intercourse before pre-intimacy. (See: al-Tibb al-Nabawi, 183, from Jabir ibn Abd llah) there are no rules and laws in pre-intimacy as to how it should be done. The only laws and rules are the ones reached by the lovers by mutual consent and often unspoken understanding. Whatever is pleasing and satisfying to both the husband and the wife is right and proper; and whatever is mutually displeasing is wrong. The only limitation to this general rule would be any Shariah rule which goes against the wishes of the husband or the wife.
pre-intimacy is Highly Recommended Islam emphasizes on pre-intimacy. Imam ‘Ali (A.S.)says, “When you intend to have sex with your wife , do not rush because the woman (also) has needs (which should be fulfilled).”

1 Sex without pre-intimacy has been equated to cruelty . The Prophet (S) said, “Three people are cruel : …a person who has sex with his wife before pre-intimacy .”

2 Another hadith equates sex without pre-intimacy to animal behavior: “When anyone of you has sex with his wife, then he should not go to her like birds ; instead he should be slow and delaying.”

3 As for the role of a woman in sexual pre-intimacy , the Imams (A.S.) have praised a wife who discards shyness when she is with her husband . Imam Muhammad al-Baqir says,“The best woman among you is the one who discards the armor of shyness when she undressed for her husband, and puts on the armor of shyness when she dresses up again.” This means that it's not good for a woman to feel shy when playing with her husband. If you are a Malama, when it comes to that, forget about your Malama things and "open fire " don't come near your husband in the night with a hijab or a niqab or some rough dressing. The decent dressing you wear when out is no longer " decent " at that moment. when you return to your husband in the night, put that away, wear tight, short, transparent dresses or go nude. Simple.

4 After all, modesty and chastity in public is the hallmark of a Muslim lady. These sayings clearly show that the husband and the wife should feel completely free when they are engaged in mutual stimulation which is known as pre-intimacy . There is nothing wrong, according to Islam, for a woman to be active and responsive during sex. As for the Islamic Shariah, all the mujtahids are unanimous in saying that the act of sexual pre-intimacy in itself is mustahab (recommended). Likewise, it is recommended not to rush into sexual intercourse.

5 The operative words is mutual pleasure and satisfaction is very important. "Talk nasty and sound silly for each other"�
Techniques of pre-intimacy
As far as the methods of mutual stimulation in pre-intimacy are concerned, the Shariah allows the husband and the wife to see, kiss, touch, smell and stimulate any part of each other’s body. Therefore, MouthAction, as it is known, is allowed though some scholars say it's undesired or disliked . Imam Musa al-Kazim was once asked, “Can a person kiss his wife’s vagina?” The Imam said, “No problem.”

6 The only restriction is that no foreign object should be used. The restriction on the use of foreign objects is based on the following hadith.‘Ubaydullah bin Zurarah says that he had an old neighbor who owned a young slave-girl. Because of his old age, he could not fully satisfy the young slave-girl during sexual intercourse. She would therefore ask him to place his fingers in her vagina as she liked it. The old man complied with her wishes even though he did not like this idea. So he requested ‘Ubaydullah to ask Imam ‘Ali ar-Reza (A.S.) about it. When ‘Ubaydullah asked the Imam (A.S.) about it, the Imam (A.S.) said, “There is no problem as long as he uses any part of his own body upon her, but he should not use anything other than his body on her.”
CAUTION: Brother, if your fingers are not clean , don't do that. It's disgusting to see some brothers with long nails, where did we learn that as Muslims? Anyway before you think of fingering her, get your hands clean and nails very short.

7 Though masturbation (i.e., self-stimulationof one’s own sexual organ till emission of semenor orgasm) is not allowed, in the case of married persons , there is no problem if the wife stimulates her husband’s penis till the emission of semen or the husband stimulates his wife’s vagina till organs . This is allowed because it does not come under “self-stimulation”; it is stimulation by a lawful partner.

Let's talk about two ayahs from SURATULBAQARAH and some Hadiths which answers the question completely.
QURAN 2:222-223
"They ask you about menstruation. "Tell them: This is a discomfort; therefore, keep away from women (do not have sexual intercourse with them ) during their menstrual periods until they are clean again. When they have cleansed themselves then you may approach them in the manner Allah has enjoined for you. Surely Allah loves those who turn to Him in repentance and keep themselves clean" Your wives are a tilth for you, so go to your tilth (have sexual relations with your wives in any manner as long as it is in the vagina and not in the anus), when or how you will, and send (good deeds , or ask Allah to bestow upon you pious offspring ) before you for your own selves. And fear Allah, and know that you are to meet Him (in the hereafter ), and give good tidings to the believers.

Allah said: Your wives are a tilth for you,) Ibn `Abbas commented, "Meaning the place of pregnanc.'' Allah then said: (...so go to your tilth, when or how you will,)