One more on the Semi-Slav -- just an introduction, there is a lot of theory to learn in some lines! 
Chess Tips
| OPENING TIPS: |
(Fine) 10. Do not sacrifice without a clear and adequate reason, eg.: <br>* it secures a tangible advantage in development <br>* it deflects the opponent's queen <br>* it prevents the opponent from castling <br>* it enables a strong attack to be developed |