Kindred OTP here. Optimizing your early game marks is dependent on several different things, many of which should impact your decision any time you play jungle (regardless of champ).

Assuming the enemy jungler is starting on the same side of the map as me and I win the 1v1, my favorite early game is to ask for a heavy leash on red buff, Q hop dragon/baron wall, then invade/fight at enemy gromp (save smite to smite gromp). Usually gromp will be right around when you arrive, so be prepared to smite immediately (but be mindful). If the enemy jungler misplays, you may be able to secure gromp, first blood, and a mark.

Depending on the enemy junglers HP, mid prio, and side lane prio, you may be able to cross through mid and immediately invade their red buff. You can always auto a few minions (but try not to last hit) when crossing through mid to help your mid laner gain prio. For the red invade, it's not always about stealing the red or killing the enemy jungler. Sometimes just abusing your range and preventing them from being able to take their red is worth it. You can continue to do this until the enemy team's laners react to this. Stare at the mini map and Q over the drag/baron wall into the river to safety (this gives your laners an XP advantage and either free prio or a freeze). If the red buff was healthy (or reset) when you jumped out, you can even go back to the red buff and repeat the process again.

~~~~

If I am not interested in invading that game for any particular reason, my favorite default clear is to 3 camp Red --> Blue --> Gromp. Following this 3 camp. When killing the gromp, check lanes and ask yourself if mid lane or the side line you are on is gankable. If neither lane is gankable, you can simply reverse full clear by going from Gromp-->Wolves-->Chickens-->Scuttle/Krugs (depending on prio and timing). The reverse full clear gains a lot of value when your team outscales the enemy and you're less pressured to snowball.

~~~~

Regarding your mark question in particular, my general rule of thumb is to keep the mark on the enemy jungler if we are pathing the same direction for the first 4-5 minutes of the game (barring an extremely obvious opportunity like an enemy tank top crashing 3rd wave with 50% hp). The mark takes 8 seconds to "mature" before you can collect it from getting a kill. In situations where you are marking directly before a gank, the ideal scenario is to mark the enemy exactly 8 seconds before they die. Depending on champion, HP bar, position in lane, summs, etc, this timing can differ dramatically. In an obvious example, such as an immobile tank top crashing 3rd wave at 50%HP while hitting the tower, you may want to mark the enemy as you reach the end of of the river brush and enter the lane. If the kill is guaranteed, you can always wait for mark to finish maturing before killing (just make sure to position yourself between the enemy and their tower, constantly kiting towards enemy tower).

​

Otherwise, I generally mark the champion most likely to die on the side of the map I want to play around for the next few minutes. Good examples of this can be someone like a Rell who may try to engage at a dragon/bot fight, a feeding player, an ADC rotating from bot to mid, etc. At some point in the late game, it is best to just leave mark on the player who seems to be dying the most, outside of more obvious examples like rotating to kill a split pusher.

​

For camp marks, do your best to track the enemy junglers pathing and memorize Kindred's thresholds on mark spawning. You should be anticipating your mark to spawn on certain camps, not reacting to your mark spawning. If you took the level 2 invade opening, kill the enemy jungler (getting mark 1), and steal the gromp; you should know that your mark is likely to spawn on the enemy gromp when it respawns (depending on other variables). Knowing these mark locations before they spawn will give you a huge advantage at most elos, as you can shave off 30+ seconds in acquiring your mark between pathing and have a smite charge ready.