Practice, practice & practice !!
I failed my driving tests 3 times and only passed at my fourth attempt. During the fourth & final attempt, I drove my friend's parents car (manual gears) and my parents car (automatic gears). I drove illegally ONLY around my house so that I could get used to the traffic and oncoming cars. I wouldn't recommend this method. Both cars were similar in size & much larger than the driving test cars here in Malaysia which are compact cars. However, we did go to an industrial area on Sunday's where the roads were free from cars & traffic and I drove the car on all routes at different speed to my heart's content.
I also had a fear of slope (going & stopping on a hill) driving and I went with my friend to a reservoir which had a slope entrance. Needless to say, I practiced going up & reversing down (very very slowly) many many times.
By the time I took my driving test, my driving instructor knew I would pass as I already had the confidence & "feel" for the car. Nowadays, I happily drive my compact car and my husband's sedan car comfortably but we opted for automatic gears as the manual gears was not an option considering we spend about 2 hours a day just stuck in traffic jams.