This article I consider to be an advanced tactical discussion how to use a DoA Blood Angels army. The basic assumption is your army is composed almost entirely of jump infantry. Possibly you have a Stormraven and maybe some landspeeders as well. You will want a high number of Marines in your army with the minimum necessary number of Sanguinary Priests for Feel No Pain. I have found two Priests works best, one is in my Honor Guard which helps save points and makes the Honor Guard more effective since the Novitiate is buffing your army, not just his unit.
Like I said I consider this article to be an advanced discussion on tactics so probably if you are not already playing a DoA style list then it's best to first start with the fundamentals, develop your confidence then come back and read this again.
There seems to be two schools of thought on how to play Blood Angels competively - the first and most popular approach is razorspam, taking advantage of cheap razorbacks for assault squads and the benefit of fielding fast vehicles. This is the easiest way to play Blood Angels competively and the learning curve is low. Mephiston is an excellent choice for razorspam, he can hide behind your transports then charge in to reap bloody mayhem. I find the DoA style of play to be more competitive but the learning curve can be steeper and takes longer to master. By mixing a couple of well placed Priests in your army you will greatly benefit from Feel No Pain, which coupled with the basic 3+ armor save is statiscally better than a straight 2+ armor save. Typically in a tournament environment you will mostly face off against mech lists. By fielding an army with a high concentration of Marines you will benefit by rendering shooting weapons designed to knock out tanks largely useless. Sure you are going to lose some Marines to lascannons and meltaguns but these weapons have a low rate of fire - they are intended to destroy armor not infantry. Once you are able to engage your opponent in assault your weight of numbers will stack in your advantage.
A smart opponent will often castle their army as a counter against a jump heavy army. This is exactly what you want versus a mechanized list since it can be exploited. Jump infantry can move 12" and charge another 6", giving them an effective 18" charge arc. The basic tenant is to land your units just over 12" away from the enemy line so they cannot assault out of their transports the following turn. You will have to absorb one turn of enemy shooting before you can assault - this is where FNP and cover are needed to help you survive that one important turn. Don't be afraid to land your jump units in terrain, you will need the cover to weather the turn of shooting. A squad of Vanguard veterans work well with this approach. Vanguard veterans can charge exposed enemy units on the drop and tie them up, denying your opponent shooting as well as provide more cover if their combats are drawn. They can also charge tanks, wrecking them for more cover or stun them for a turn to prevent them from shooting as well. Once you have charged in the rest of your army the next turn you'll be where you want to be. So the premise is to land your units just outside the charge arc of your opponent's units, absorb a turn of shooting then charge. By having a couple of Priests well placed along your peripheral line the majority of your army has FNP plus some cover. The Descent of Angels special rule for jump packs means you will have minimal scatter so you can confidentially place your units where you need them to be plus the majority of your army will arrive on Turn 2. I have found this tactic does very well versus both Space Wolves plus mechanized IG. Sometimes it is more beneficial to drop your units in close enough so that your meltas can pop armor. Blood Angels with FNP are just as survivable as Grey Hunters.
So you may want to stagger your line putting some of your units in assault range of the opponent, hopefully drawing them out. You can then counter charge with the rest of your army and benefit from Furious Charge. The staggered line is the best approach versus IG as you must quickly destroy their tanks with close ranged shooting then assault - it can be their worst nightmare if done right. This is a bloody way to play Blood Angels and I think it suits their background well. You do have to be confident though. If you are on the fence it wont go well.
A note - this style of play does not work well versus Tyranid and ork hordes. Tyranids will bubble wrap their monstrous creatures with gaunts. You'll cut through the gaunts then they will counter charge you with their big nasty bugs - it just doesn't work well as you won't have enough long ranged shooting to drop enough of the big brutes. Ork hordes can absorb your charges and assault out of their open topped transports. I think the same will be true for dark eldar as well - they can match your speed and use fleet to counter charge your units before you can engage them. So the peripheral assault is designed to be used versus armies like IG and SW. If you try to use this tactic blindly you'll end up losing when another approach could have worked better.