Wrestling take downs

Double leg BJJ: hit the hips and back of knees ,  head down to drive opp straight to matt
Double leg Greco Roman:  hit the belly and grab back of hamstrings,  head up to drive opp up for slam, or pivot around head for side slam and control.
Heavy opp Double to Side control: hit hips and bang lead knee,  step rear leg through to side ,  staying in low base trap ops lead knee  and block his rear for side control  drop.

Single Leg:  hit hip/ inner thigh, inside hand back of knee,  outside hand heel. Crank leg up , head down and tight on leg to avoid guillotine  choke.  finish by cranking high and pushing shoulder into inner thigh , or use lead leg to trip their rear leg.

Knee Block: Get dominant position.  (get head under theirs,  bend knees,  so hips lower than theirs,  thrust hips/ lead leg forward into their lead leg to straighten it). bend to outside,  block front side of knee joint and push them over the block.   

Boxing : Reaction and counter punching

The two main things you need to do when on the back foot are...
1. remain assertive (don't become defensive):  by focusing on the chin by saying "chin" especially when hit.
2.  Layback;  to give you more space to execute your attack.

Strategies:
1.  stay on the centre line use long rhythm and covers to nullify attack until you have a good countering opportunity.
2.  offset the centre line.  you must not walk in circles or you will walk into a right or left hook.  however taking 1 1/2 steps either way of the centre line and then maintaining this offset will enable the looping jab and slip and rip right uppercut.

Boxing: Being First / The Aggessor (Explore all angles, poker face when you see an opportunity to enable an inch in)

The saying "be first" is very confusing in boxing as from my own personal experience it requires a lot of patience.

ultimately one need to maintain a poker face as if you rush in from a static position when you see an opportunity this will clue up your opponent to the fact that you have seen an entry.  They may not know where there mistake is but they will react by either running away or putting up full cover.

The most simple and effective way to be first / the aggressor is to pace and aim, when you see an opening,  lay back (poker face and optical illison) so that you can inch in without your opponent cottoning on. then when in range drive or lunge.

Being first requires patience and pro activity.  If you simple wait static for your opponent to make a mistake you will be waiting a long time.  so we must incorporate some lateral movement of the head,  not to evade punches but to examine every angle available to you to attack to ensure you are not missing any potential opportunities.

I guess like I keep saying focusing on the hitting the chin hunting for it a little is the best mindset whether on the front or back foot.