Here's a list of some things I've done to migrate OSX from 10.9 to 10.14 on my MacBook Pro. If you brick your computer trying a hack listed here, it's not my fault.
If you're not comfortable messing around with the command line, turn back now.
defaults write com.apple.Terminal WindowBorderMinBrightness -int 0
defaults write -g NSScrollAnimationEnabled -bool false
<key>UnifiedSleepSliderPref</key> <false/>
defaults write -g ApplePersistence -bool no
defaults write -g NSUseAnimatedFocusRing -bool no
defaults write /System/Library/LaunchDaemons/com.apple.mDNSResponder.plist ProgramArguments -array-add -DisableSleepProxyClient
pmset dwlinterval 1
defaults write org.my.app NSRequiresAquaSystemAppearance -bool no
defaults write com.apple.systempreferences AttentionPrefBundleIDs 0
defaults write xcodebuild IDEBuildOperationMaxNumberOfConcurrentCompileTasks 5
hidutil property --set '{"UserKeyMapping":[{"HIDKeyboardModifierMappingSrc":0x700000065,"HIDKeyboardModifierMappingDst":0x7000000E7}]}'
defaults write -g AppleEnableMenuBarTransparency -bool no defaults write -g NSDocumentSaveNewDocumentsToCloud -bool no defaults write -g AppleShowScrollBars -string "Always" defaults write -g NSNavPanelExpandedStateForSaveMode -bool yes defaults write -g NSAutomaticWindowAnimationsEnabled -bool no defaults write -g NSAutomaticSpellingCorrectionEnabled -bool no defaults write -g AppleShowAllExtensions -bool yes defaults write -g CSUIDisable32BitWarning -boolean TRUE defaults write -g defaults write com.apple.LaunchServices LSQuarantine -bool no defaults write com.apple.finder AppleShowAllFiles -bool yes defaults write com.apple.finder ShowStatusBar -bool yes defaults write com.apple.finder QLEnableTextSelection -bool yes defaults write com.apple.finder _FXShowPosixPathInTitle -bool yes defaults write com.apple.screencapture location ~/Pictures/ScreenShots defaults write com.apple.Safari DebugSuppressAlerts -bool yes defaults write com.apple.Safari DebugShowProcessIDsForPerTabWebProcesses -bool true defaults write com.apple.Safari DebugSuppressAlerts -bool yes defaults write com.apple.Safari ShowStatusBar -bool yes defaults write com.apple.Safari IncludeInternalDebugMenu -bool yes defaults write com.apple.Safari FindOnPageMatchesWordStartsOnly -bool no
defaults write com.apple.DiskUtility DUDebugMenuEnabled -bool true defaults write com.apple.DiskUtility DUShowEveryPartition -bool true defaults write com.apple.DiskUtility advanced-image-options -bool true