TFS 2015 Vnext build gives you the option for running Visual studio build which will ideally have these options

1) Get Source
This action is Hidden but as you can understand TFS will download source files from TFS based on your settings on Repository for Mappings to Source. There are chances that it will complain about files already exist
Warning C:\Agent\_Work\4\s\Tests\project.xml - Unable to perform the get operation because the file already exists locally
Warning C:\Agent\_Work\4\s\Tests\project - Gateway - .xml - Unable to perform the get operation because the file already exists locally
One or more errors occurred while performing a get operation for workspace ws_4_9;Build\5a940eb8-a66f-4dc3-a742-ad23cee5dc01
The quick Solution is always clean the workspace before starting the new build.

2) Nuget Restore
If you are using Nuget restore in your build and if you have some Local repository for your Nuget , TFS nuget Restore will fail for any Local Nuget package download
2016-10-12T05:30:08.1016689Z Set workingFolder to default: C:\Agent\tasks\NuGetInstaller\0.1.18
2016-10-12T05:30:08.1173069Z Executing the powershell script: C:\Agent\tasks\NuGetInstaller\0.1.18\NuGetInstaller.ps1
2016-10-12T05:30:08.4766837Z C:\Agent\agent\worker\tools\NuGet.exe restore "C:\Agent\_Work\4\s\Services.sln" -NoCache -NonInteractive
2016-10-12T05:30:08.8204175Z MSBuild auto-detection: using msbuild version '14.0' from 'C:\Program Files (x86)\MSBuild\14.0\bin'.
2016-10-12T05:30:22.4923248Z ##[error]Unable to find version '2.0.5939.19993' of package 'FOO.Logging'.
2016-10-12T05:30:22.5860716Z ##[error]Unexpected exit code 1 returned from tool NuGet.exe
To avoid this issue when we setup the Build Agent we should be running it with our domain account which has access to this Nuget Repository and not with default Account NT Authority\Network Service
3) Copy and Publish Build Artefacts
This action fails with "TF14044: Access Denied: User Project Collection Build Service needs the Admin Workspaces global permission(s).".
To Avoid this issue we need to install TFS 2015 Update 3
4) TFS 2015 Build Clean up
TFS 2015 Build clean-up is daily bases and not on count. I am not fan of this logic because we have 4-5 Projects running simultaneously and continuous build will occupy lots of space. Plus, I like to retain some baseline release builds for longer period.
So I have created quick PowerShell script for clean-up and scheduled it as Command line in TFS build.
I am using 2 for keeping latest 2 builds and delete anything older than that. You can retain more number of builds by increasing that number.
"Get-ChildItem '\\dev-exe-002\drop\* ' -Directory | Sort-Object CreationTime -Descending | Select-Object -Skip 2 | Remove-Item -Recurse -Force"
Add Command line in your build step and provide parameter like
