1. Confirm the correct CIF value of what you intend to import
2. If your goods aren't subject to duties/taxes (your agent or kra can check that out,please ensure that you get an Exemption letter from the concerned bodies, well in advance to avoid storage costs arising out of delays in getting the letter after arrival-it can take weeks.
2. Do things right and PAY due taxes/duties/levies.Avoid cheap shortcuts.Your PIN details get registered with KRA so the day you will be caught,could be years later you will pay a hefty fine or be penalized altogether until you pay back what you stole from KRA. Your agent may also get penalized for deliberately processing entries using low valued invoices and evading tax just to keep his costs low.
Rem that Customs officials keep rotating,don't take chances.
3. Do not undervalue the goods-CRSP will find you out as suspicious low valued goods are taken for further valuation before entry is passed.
4. Most important-Do not ship commercial goods into Kenya without a coc ie if applicable.
5. Use registered agents.Confirm that your agent,briefcase or not is still registered as a customs agent at the time of clearance.
6. Finally Duty % is based on the type/category/HS code of goods and not the cost of goods.

Good luck,najua wakenya hawapendi kusikia hii.