in addition to your pe... kegels. do kegels and get used to doing them regularly. if you're doing phase 1 you should already be doing them anyway. search the forums for more information on them if you need to.
quit or cut down smoking if you do (i'm guilty of this), drink lots of water, get more exercise and eat healthier, especially if you don't want to take any supplements. if your blood is too fatty you'll get clogged up. good bloodflow is important. look at your lifestyle and see what you can improve a bit.
also, get erections more frequently. even if you can't get completely hard every time keep doing. the more you get them the easier they'll be to get eventually.
do some relaxtion/meditation exercises. i find that the more stress/nervous i get, the more difficult it is for me to get an erection no matter how much i touch and try to get one. when i am relaxed is when i get the hardest ones, often without touching. i'll just look down and be like, "ooo, look at you!"
so relax now. if you worry too much about getting the hardest erections you are probably not gonna get one.