blowjob troubles help!

fern
so i'm new to blowjobs and now i've 'given' about 3 or 4. i can never just do the whole thing in my mouth i have to stop and do some with my hand and continue in the mouth. i was wondering how long it takes for anyone else to completely finish them off and if you do it entirely in your mouth. can anyone give me any tips on how to give amazing blowjobs? 
he says that meanwhile doing it it feels great im just really slow