What works well for me: 1. Split the project into tasks. (a task taking at least 3-5 PTs) 2. Have a POC / prerelease phase 3. For complex tasks introduce a s

What works well for me: 1. Split the project into tasks. (a task taking at least 3-5 PTs) 2. Have a POC / prerelease phase 3. For complex tasks introduce a second polishing task, like "Basic User management 1/2" and later "Basic User management 2/2". If the second one isn't needed: Great! 4. For all tasks/areas estimate a lower and an upper estimation in hours or PT. 5. Revisit your estimation afterwards using this process: 5.1. Imagined that someones gives you the following choice: You get 1000$ if your the true value lies within your estimation 90% of the time. Or you can roll a dice and in 9/10 you get the 1000$. 5.2 If confidently pick your estimation ("I'm 100% sure the true value is within my bounds") then it's too wide. 5.3 If you rather pick the dice-roll, then you don't trust your estimation, it's too narrow. 5.4 Adjust your estimation until both options seem equally probable to you: dice-roll or your estimate being true 90% of the time.