Some formulas seem to represent older layers of texts, and I collected practice advice around the formula “How you should train yourself” (evaṃ sikkhitabbaṃ). I believe that we find here among the best Early Buddhism has to offer.
We find the formula mostly in SN and AN, only few in MN, and not at all in DN (which I take as a sign of the formula’s old age). The practice advices fall into a few categories: general conduct, conduct of monastics, meditation and its prerequisites.
Most of the advices are very short, even though some extend into longer strings (especially in the MN). Here I list only some short ones in the hopes that you find inspiration in it. 
I will be one who has good friends, good companions, good comrades. SN 3.18
We will abandon the arisen gain, honour, and praise, and we will not let the arisen gain, honour, and praise persist obsessing our minds. SN 17.1-43
We will dwell diligently. SN 20.1, SN 20.2, SN 20.6, SN 20.11
We will develop and cultivate the liberation of mind by loving-kindness, make it our vehicle, make it our basis, stabilize it, exercise ourselves in it, and fully perfect it. SN 20.3-5
We will be grateful and thankful, and we will not overlook even the least favour done to us. SN 20.12
Even though I am afflicted in body, my mind will be unafflicted. SN 22.1
We will guard the doors of the sense faculties; we will be moderate in eating; we will be devoted to wakefulness. SN 35.120
We will develop and cultivate mindfulness directed to the body, make it our vehicle, make it our basis, stabilize it, exercise ourselves in it, and fully perfect it. SN 35.247, SN 47.20
We will dwell with a mind devoid of conceiving. We will dwell with an imperturbable mind. We will dwell with a mind devoid of palpitation. We will dwell with a mind devoid of proliferation. We will dwell with a mind in which conceit has been struck down. SN 35.248
We will increase in wisdom. AN 1.77, AN 1.79, AN 1.81
We will obtain the taste of the meaning, the taste of the Dhamma, the taste of liberation. AN 1.347
We will fear the fault pertaining to the present life; we will fear the fault pertaining to the future life. We will be fearful of faults and see peril in faults. AN 2.1
We will strive for the relinquishment of all attachments. AN 2.2
We will have peaceful sense faculties and peaceful minds. We will offer only peaceful service to our fellow monks. AN 2.36
Striving in successively higher and more sublime ways, we will realize the unsurpassed bliss of liberation. AN 5.180
We will dwell heedfully. We will develop mindfulness of death keenly for the destruction of the taints. AN 6.19, AN 8.73
We will purify our bodily action, our verbal action, and our mental action by repeatedly reflecting upon them. MN 61
We shall be wise men, we shall be inquirers. MN 115
We will enter upon and abide in pure, supreme, unsurpassed voidness. MN 121
We shall know the state with conflict and we shall know the state without conflict, and knowing these, we shall enter upon the way without conflict. MN 139
