Budget is quite low for good results. You can start with keyword research and try to find mid competition keywords. You can try appradar free account for 20 keywords or use theyr free trial account. Look for relevant "orange" keywords. AppTweak is good as well and was the first tool I used. Then write a good app title and description but dont stess out wth suggestion from appradar. Check competition and add kw in the title. Next you need keyword installs - make sure they are high retention. keyapptop and appranky are good. Your goal is to rank for some keywords, get some traffic and start to make money asap. ASO is just like SEO there is white hat and black hat, you cant see instant results and there is no guarantee. Ranking takes time and nobody can guarantee. Stay away from rank guaranteed services. Usually you can rank first for long tail keywords with low score in appradar. beaware no rank tracking service works fine as the search is personalized. some of my keywords are in top 10 for keyapptop while they are below top 100 in appradar. I use appradar for tracking not because they are the best but i like the interface and it is better to stick to a tool - this way i see when keyeords and going up or down not paying much attaention to if they are ranked #3 or #17. Traffic is what matters and revenue. Some keywords are bettet than others in terms of revenue. good luck.