Hey there! Search and Destroy is my favorite game mode, so let me share some of my basic tips and knowledge with you about it!
It is played on any of four given maps:
Warhead - small urban
Sand Hog - small urban
Snow Valley - large arctic
Gray Hammer - large urban
Depending on which side you are on, there is an objective. If you are on Alpha team, your objective is to either kill all of Bravo team, or successfully plant the bomb without it being defused. If you are on Bravo team, your objective is to guard the bomb sites and either kill all of Alpha team or defuse the bomb once they plant it. If the bomb explodes or you all die, you lose. Same for Alpha- if the bomb is defused or you all die, you lose. Also for Alpha- if the given time limit runs out and you haven't planted- you lose and Bravo wins.
Basic Tips
ALPHA
-Don't rush and plant. If you are planting make sure teammates are around you and if they die, apparently an enemy is nearby and you should help them out. If your teammate is planting, don't be stupid and watch him or try to plant yourself... guard him. Make sure no enemies come and alert him if they do.
-Stick together or split up evenly. It pays off not to go alone or in small groups, unless you are very skilled.
-Don't frigging camp! If you don't know, camping is when you stay at a certain spot and wait for enemies to come so you can kill them. For God's sake, don't sit at your base and wait for them to come to you. They probably won't. ALPHA TEAM WILL LOSE IF THE GIVEN TIME LIMIT RUNS OUT AND YOU HAVE NOT PLANTED. Dang.
BRAVO
-Defend! Don't rush to THEIR base. They are Alpha, they'll come to you. Don't think a surprise attack will work, unless they are all noobs. They'll be fully alert, I assure you. Stay at your bomb sites or outside of them and make sure Alpha team does not plant. Camping is a good thing if you're on Bravo.
-If you happen to be in a situation where you are the only one left on your team and the bomb is ticking away, don't fool around! Get to the bomb and defuse it! Look at the bomb and hold E to defuse it. It has to give you the option to press E before you do it.
I don't know what else to say. I'm tired right now.
Hope I helped. ^_^