@Mawinder, true entreprenuer!
My two cents 4 u though:
1. To be successful as a contractor, u hav to be very disciplined in terms of
cashflow management. This is what messes most of our contractors. in this business, u really hav to keep be very good in supply chain management that is knowing how much and when to order materials so that u'l be able to balance between labour and materials.
Usije ukapewa certificate ya kwanza uende ununue cement ujaze kwa workshop, ama ukanunue Range rover.

Most contractors usually have cashflow problems n they find themselves unable to pay for labour bcoz they bot materials with all the money paid ama waliongezea mabibi.

Since ur undertaking Govt/cdf/community projects, u should always make sure that ur very keen on the
payments. U shud expect to work n not be paid, it always happens. Be careful not invest ur all in a project, these kind of projects can take u back to zero
Contracts = Before u start any job, always make sure u have a well documented contract signed by u and ur client as this will for a basis of ur claims in case of abortive works. Also make sure u read and understand ur contract well especially on the payment clauses, fluctuation clauses, termination clauses, variations, dispute resolution... Very important.
Documentation => As a contractor, ur key weapon is documents.. if an instruction is issued to change scope of work or introducing new work, always make sure that is in writing or else u confirm in writing to the engineer or the architect. All verbal communications with cost implications.. always in writing.. this will come in handy if something goes wrong in future during which time ul have basis for ur claims. Document ur daily activities, update & impact ur programme of works, request for details in time and in writing.... all this will be helpful incase u have not completed the project in the contract time and u need to request for an extension of time as u will be required to give proof. Most clients will charge damages if u dont finish in the agreed time.
Payments - ensure payments are on time as per contract and charge interest for delayed payments.