The following sentence from question motivated/inspired me to introduce following two steps:

Ok, I understand there are lot of Hindu scriptures.

Step-1 Know about Hindu scriptures.

First of all you should get the basic knowledge about Hindu scriptures, you can read following articles:

The following posts can also help you regarding it:

The following part from question is also included in the this step:

I wish to read them for - meditation - to gain wisdom/knowledge And which texts do you recommend for beginners? Would Bhagavad Gita, Rig Vedas be good start?

Step-2 Select the scripture for reading.

This is an important topic to consider. After getting basic knowledge about Hindu scriptures, you can decide which scripture to select reading. In this step you are supposed to choose the scriptures according to your interest and intellect. This also includes How can one know which path among karma, bhakti and jnana is suitable for him?. In other words, according to the intellect and spiritual-level specific path among Jnana, Bhakti, Karma and Raja Yoga may be suitable. Following are some recommendation:-

Considering the title of question

Step-3 How to read scriptures.

For Vedas & Upanishads, it is better to learn Vedas under the guidance of Guru instead of just reading. Visit already asked related questions : Start reading Hindu Vedas and What order should I read the Vedas and Upanishads in?.

For Bhagavad Gita, we've already a post How to start reading Bhagavad Gita? which may help you.

Here are some general guidance:

As per my observation and experience, for many scriptures (talking about purchased hard copies), when you start reading you'll find the instruction given for the method of reading. Some prescript and guidance should be given on Ramayana, Mahabharata, Puranas etc. scriptures. You can follow it.

The following topics from question can be solved by considering following things

-raise positive vibrational energy - but most importantly break out of bad karma do (I believe in reincarnation)

Common things to consider are: Open mind: It is very important to grasp/absorb the knowledge. Positive thinking : It is also important for ensuring that the true goal is not getting diverted/distorted as well as for establishing supportive/favorable nature of mind/intellect for interpreting texts. Shradhha (faithfulness/trustfulness/reverence) in Bhagavan/Ishwar as well as in scriptures you're reading. Maintaining Satva Guna over Rajas and Tamas. You can read some qualities of Satva from Bhagavad Gita Adhyaya 18 verses- 9, 10, 20, 23, 26, 30, 33, 51-53 etc. Nishkama Karma helps in Chitta Suddhi (purification of mind) which is necessary in spirituality.



Considering following topic from the question

Can I read it continuously till I finish, and then start again?

Or are some parts read during some times of the day.

There is no strict rules to be followed but as earlier discussed, it depends upon your interest, intellect and the level of spirituality or as guided by Guru.

The general tip/guidance would be: Generally the scripture is divided into some parts called Adhyaya (अध्याय). You can allocate certain time for one Adhyaya daily according to the length of Adhyaya and the time you're going to provide everyday or alternatively as per your convenience but once you've decided and started to reading, then it is expected to follow it regularly with concentration.

Additional Notes:

Following part is suitable for spiritual readings like Upanishads/Vedanta:

Note that just reading scripture only is not enough/effective. Learning of scripture includes three steps/aspects: Shravana, Manana and Nididhyasana.

Shravana means listening the thoughts or gist/significance of Shruti from Guru. Here you can roughly compare it with reading scriptures.

Manana means deep thinking/reflection or consideration/contemplation on what is listened (here you can roughly compare it with what read) in first step.

Nididhyasana means repeated meditation (Dhyana) on the true sense of scripture (more precisely absolute truth of Upanishad) till it gets realized!

Above aspects are explained in Panchadasi and Sarva Vedanta Siddhanta Saar Sangrah.

Quoting some related verses on it:

From Vivekachudamani: श्रुतेः शतगुणं विद्यान्मननं मननादपि ।

निदिध्यासं लक्षगुणमनन्तं निर्विकल्पकम् ॥ ३६४॥ 364. Reflection should be considered a hundred times superior to hearing, and meditation a hundred thousand times superior even to reflection, but the Nirvikalpa Samadhi is infinite in its results.

From Brihadaranyaka Upanishad 2.4.5: आत्मा वा अरे द्रष्टव्यः श्रोतव्यो मन्तव्यो निदिध्यासितव्यो मैत्रेयि,

आत्मनो व अरे दर्शनेन श्रवणेन मत्या विज्ञानेनेदं सर्वं विदितम् || The Self, my dear Maitreyi, should be realized – should be heard of, reflected on and meditated upon; by the realization of the Self, my dear, through hearing, reflection and meditation, all this is known.

At last let me quote one interesting verse from Mundaka Upanishad:

तत्रापरा ऋग्वेदो यजुर्वेदः सामवेदोऽथर्ववेदः शिक्षा कल्पो व्याकरणं निरुक्तं छन्दो ज्योतिषमिति । अथ परा यया तदक्षरमधिगम्यते ॥ ५॥ 5 Of these two, the lower knowledge is the Rig—Veda, the Yajur—Veda, the Sama—Veda, the Atharva—Veda, siksha (phonetics), kalpa (rituals), vyakaranam (grammar), nirukta (etymology), chhandas (metre) and jyotisha (astronomy); and the Higher Knowledge is that by which the Imperishable Brahman is attained.

Hope this would help you in 1.Knowing about Hindu scriptures 2.Selecting scripture for reading 3.How to read scripture and some general guidance for proper/effective reading and getting the true knowledge from Hindu scriptures.