It can be annoying when a web site link automatically opens up a new window, especially if you prefer tabs to windows. You can force all of these kinds of links to open a new tab by using the Terminal and changing a Safari preference. Simply type: defaults write com.apple.Safari TargetedClicksCreateTabs -bool true
Related: Drag Tabs to Windows in Safari, Open Tabs From Top Sites, Creating New Tabs In Safari, Disappearing Tabs in Safari, Cycle Through Safari Tabs.

thank u very much for this tip!
actualy i love safari but this was the most unnoying thing in this browser,
o.k. i got used to click cmd key on the link for opening a tab. but now its more practikal like , oprating your lap top on bed or horizontal position for example.
Keep on sending these little secrets !!
Peace :)