“I am not that good in algebra.”
Algebra is a fundamental building block upon which engineering and math are built. To do well at engineering or math, algebra has to be about as difficult as brushing your teeth – you just do it without thinking.
“Your goal here should not be to simply memorize recipes …”
I agree completely. I can still remember during exams (years ago) forgetting the formulae and having to re-derive them from basic principles in the margins of the exams. Of course I was helped by the fact that a week earlier I had known the formulae. To do well you need to understand the concepts well. Memorizing formulae will not get you very far.