Dear Wessam, in my opinion, in this case there are at least 4 main steps that must be taken:
1- financial, to calculate the target valuation, historical results and future projections to validate the achievement of defined goals, margins, growth, etc.
2- legal, to assess the contingencies existing in the company you intend to join as a partner to delimit the buyer’s responsibilities, in addition to drawing up a good shareholders’ agreement with clear rules on the rights and responsibilities of each partner (e.g. veto power, number of seats on the board, etc).
3- Commercial, to assess the business model, the position of the target vis-à-vis the main competitors, whether the proposed projections are feasible and attainable according to the company’s history. If the target has the skills the buyer wants.
4- Technical, depending on the industry and objective of the deal, it is important to know and evaluate, for example, the product that the target has (quality, right to win, differential, security, compliance, etc).