Tides (de_tides) is not a popular map among the Counter-Strike community. It has narrow pathways and enclosed areas. To make matters worse, the bridge and bombsite A (the only major pathways for players) is often guarded by snipers.
Smoke grenades are highly recommended to use in order to fend off snipers in the bridge and bombsite A. Although the hallways and the middle may seem appealing to traverse through, ambushes are very common and players armed with shotguns can easily overwhelm enemies. Rushing through the bridge in later rounds is often a poor choice without backup thus players may prefer to move to bombsite A as it's possible to throw some smoke grenades to conceal movement.
The middle is usually an important area in Tides as it's located in the very middle of the map and serves as alternative routes to access the bombsites.
Bombsite B/CT Spawn Zone
Usually, combat does not occur here as fighting is limited to the bridge, unless the Terrorists were able to overwhelm the CTs.
CT players may camp in this area but it is often a poor choice as the Terrorists can easily rush into this bombsite or they can guard site A, hindering the Counter-Terrorists if they have to defuse the C4.
Snipers are not common here unless the Terrorists have decided to take over this area. Primarily, Terrorist snipers will usually be located at the long hall or at the bridge when the bomb was planted in this site.
Bombsite A/Long Hall/Middle
CT snipers will often have the advantage here as they can occupy the long hall and snipe the only entry/exit point from the Terrorist Spawn Zone. Essentially, it is often preferable to guard Bombsite A at the long hall than any other part of the site as it is too open-spaced.
Terrorist players will avoid taking the side hall and entering this area as they can be eliminated by a CT sniper at the long hall. However, this is a good place to rush into in the pistol round.
Alternatively, the middle is another pathway for the Terrorist team to use, provided that activity was not centered in the bridge. This usually allows players to counter snipers at the long hall. Vice versa, CT players may try to infiltrate through the middle if Terrorist snipers have pinned down other allies in the long hall and the side hall.
Should the Terrorists somehow prevail, they can plant the bomb here and camp at the long hall which can cause trouble for the CTs as it's fairly easy to guard the three major entrances with sufficient snipers.
A player can jump on a ledge and ambush enemies from above, With the aid of a smoke grenade, he can conceal himself and fire at assailants, especially at the side hall entrance.
Similar to the windows at the bridge, CTs snipers can prevent the Terrorist force from reaching this bombsite. Somewhat ironically, the Terrorists can also use this section to guard the planted bomb from a far distance.
With backup, this is a good area to rush in the pistol round. However, be sure to have at least two members to guard either the Windows (as a Terrorist) or the hallway between the CT Spawn Zone and the bridge (as a Counter-Terrorist). It is important for assistance to be located on the upper ground to prevent being swarmed from the lower elevations of the Bridge.
Smoke grenades are heavily used here to counter snipers. Primarily, they are thrown at potential snipers nests or at pathways where snipers can watch.
If the long hall has been occupied by enemies, it's very likely that the Counter-Terrorists will be at the bridge to move towards the middle or the side hall to gain access to bombsite A or B.
Flashbangs are also good to use but they can also blind your team members due to the enclosed space.
HE grenades can be used at clustered groups of enemies. Moreover, they are hard to avoid in certain places.
Terrorist snipers have the main advantage here as they can rush to this area first and eliminate the CTs. Note that HE grenades can be thrown into this enclosed area and can inflict high damage.
Terrorist Spawn Zone
Terrorist players can get held up here if a CT sniper has them pinned, unless they have a smoke grenade. Sometimes, as a last resort, the CTs may choose to move through the side hall to reach the C4 if it was dropped in Bombsite A.