As stated, check the tutorials first.
To be quite honest, i can never understand after someone has had training they cannot blend tips, unless they have had inadequate training or an ignorant tutor.
If you can't blend tips, you should not be allowed/able to progress to putting acrylic/gel over the top (unless it's to teach you what not to do). Do teachers actually supervise students?
It's quite simple,if you can still see them afterwards, you are not blending properly, next time blend them more, you may even overblend on occasions, if thats the case, blend them less.
Everytime you do a nail (or blend) you should be teaching yourself.
If your teacher is too lazy to supervise/show you, then you will have to learn from your own mistakes!!!!
A secret ingredient for anyone in training is common sense (your own).
Here are some examples of common problems & their solutions:
Tips not buffed in enough = buff em in more (and visa versa)
Nails too thick = make em thinner (and visa versa)
Product too wet = make it dryer (and visa versa)
Too much adhesive = use less adhesive (and visa versa)
Sorry to sound cynical/sarcastic, but sooner or later you do have to go it alone without constant guidance and you have to think for yourself.
Even though we/you/I are very lucky to have a forum such as this, the most important person you should be asking questions of and seeking answers from is YOURSELF.
Also if you are having problems with the "basics" after training (yes tip blending is a "basic" procedure), you should be asking for a refund, as you obviously have not got what you paid for.