I push /pull most long bows up to about 55# but use a stringer or my shop pegs for recurves and hybrid LB's.
A lot of it has to do with experience with a push pull method, and your strength and dexterity of your fingers. The ability to put the weight of your limb on the heel of your hand and manipulate the loop with your fingers is needed. I can string a bow up to 60-65# with a push/pull method, but taking the string off i have problems over 55#.....
The safest way is to use a stringer. and use the RIGHT stringer for the bow. A tip to tip long bow stringer should NEVER be used on a recurve, and i don't recommend them for R/D long bows either....
Those tip to tip stringers should be outlawed IMO, Most bows are not designed to have all that pressure right on the point of the tip overlays.
I always recommend a stringer with a deep pocket that holds the string in place on the lower loop, and a rubber saddle on the other end that puts the pressure on the back of the limb..... Selway Recurve stringer is the best i've found.
For guys that use a step though method for recurves, i recommend using a rubber band to hold the string in place on the lower limb while setting the string in the upper grooves. A good step though style works very well if you have the strength to bend the limbs evenly without twisting them.
If you just use common sense and watch how the limbs are bending as you put pressure on the limbs you'll be fine. Whether you are push/ pulling, or using a step though method, or a stringer, make damn sure you are not twisting them & you will do no damage.... that goes for letting off the pressure too.... watch your limbs closely as the string takes the load.
Then very carefully look at the string grooves from the belly side of the limb , instantly and make sure they are laying in the grooves properly. This requires flipping the bow over as soon as the string takes the weight..... MANY guys have been slapped in the face by not flipping the bow around before inspecting the string fit....Some have even lost an eye....
One more thing to add about stringing a bow. Once you have it strung, and the string looks good on each string groove. Don't hang it up ans walk away. You should ALWAYS draw the bow a couple times to make sure that string centers up properly in the grooves.
Care and maintenance of your string grooves is something that is often overlooked. Some times you can get a wax build up and dirt that can cause problems. every now and then take some time to pull your string off and polish up your string notches with a piece of yarn or small parachute cord. Then clean and wax your string loops while you are at it. I like to heat my bee's wax with a heat gun or hair drier when doing that to make sure its smooth and not sticky.
Often times i'll take a little vaseline and rub inside the loop. especially in cold wet weather.
Sorry for getting so long winded here guys... but i've seen more bows ruined from stringing bows incorrectly than just about anything else. Mostly recurves. Stringing bows over 50# can be simple, or down right dangerous depending on how you go about it....... Be safe... & be good to your bows... Kirk