The name of the Lord is your sole refuge. It is your prop, shelter and abode. Name is divine nectar. Name and form are inseparable.
Keep a picture of the Lord and concentrate on it. Concentrate on the face or feet or the whole picture. Then visualise this in your heart or in the space between the eyebrows.
Repeat your mantra Om Namah Shivaya, Om Namo Narayanaya, Om Namo Bhagavate Vasudevaya - mentally, or if the mind wanders, do this verbally.
There are five kinds of bhavas or attitudes. They are shanta bhava (relationship of peace), dasya bhava (relationship of servant master), vatsalya bhava (relationship of father son), sakhya bhava (relationship of friendship) and madhurya bhava (relationship of lover and beloved). Have any kind of bhava that suits your temperament. Develop it again and again.
Practise the nine modes of devotion shravana (hearing the lilas or stories of the Lord), kirtana (singing the Lord's name), smarana (remembering the Lord), padasevana (service of the Lord's feet), arcana (offering of flowers), vandana (prostration), dasyam (servant bhava), sakhya (His friendship), and atmanivedana (self-surrender).
Feel that you are an instrument in the hands of the Lord. Feel that the Lord works through your body, mind and senses. Offer all your actions to the Lord. Offer the fruits of your actions to the Lord. This is the way to do self-surrender.
Do anusthana (intense whole time practice) frequently. Live on milk and fruits for a week.
Observe mauna (or silence). Do japa (repetition of God's name) and meditate in an intense manner.
Do mental worship - it is a great help for increasing devotion and attaining concentration. Offer flowers, incense etc., mentally, to the Lord.
God is all pervading.
God is all permeating.
God is interpenetrating.
God is indwelling.