" 1. Go full paragon or renegade for full effect. 2. Every upgrade is important. 3. The game tracks how urgently you approach some missions. 4. *most* importantly; it's very unlikely your 1st time trough will be a perfect success, so just enjoy it. Then Newgame+ it. "
This is great advice. I would also advise you to take your time. As the late, great John Wooden might say, "Be quick, but don't hurry."